JP2002521174A - Filtration element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost filter element in which the characteristics of a hydrophilic filter medium do not cause adverse effects such as damage when embedded in a fixing element. SUMMARY The present invention relates to a filter element using a hydrophilic polymer filter medium, particularly a wound and / or pleated filter medium, embedded in a fixing element such as an end cap and / or an adapter. In order to effectively embed the filter medium in a fixing element, it is important to monitor the melting point or glass transition temperature of the filter medium and the wettability of the end cap material. As claimed in the present invention, the thermoplastic elastomer used maintains a rubber-like elastic state at low temperatures so that no deformation remains, and enters a viscose state at a relatively high temperature, and in this state such as a thermoplastic resin. It is a polymer that can be processed into This thermoplastic elastomer is exactly the same as a thermoplastic resin, and can be processed into a fixing element having the advantage of a relatively low temperature of 180 ° C. or less. Depending on the chemical structure, these materials have a pronounced hydrophilic character with a certain flexibility. This is particularly advantageous if the highly reactive membrane material is embedded. Preferably, the thermoplastic polymer is a polyether-polyamide block copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a filtering element using a hydrophilic polymer filter medium embedded in a fixing element such as an end cap and / or an adapter.

[0002] Porous filter membranes are produced from the most variable thermoplastic materials such as polypropylene, polyamide, aromatic polyamide, polyimide resin, polysulfone, polyethersulfone, cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, etc. .

[0003]

[Prior art]

These filter membranes are often further processed into fusing or winding forms which are ultimately processed into fusing elements, most often into so-called membrane filtration tubes which are embedded in so-called end caps. U.S. Pat. No. 3,457,339 describes how to make these filtration elements. Membrane filtration tubes produced using these or similar methods, after wetting with a suitable material, have a pore size in the range of 0.04-5 microns of the used membrane material. When in
In particular, it has the feature that its integrity can be tested.

[0004] Most often, water or aqueous solutions are used to wet the membrane filtration tubes. Wetting of the filtration element can be done more easily the more hydrophilic the components used are. For this reason, in many cases of so-called aseptic filtration of liquid resins, hydrophilic membrane materials such as polyamide or cellulose derivatives are used. However, depending on the use and requirements of the membrane material, it is necessary to use another membrane material having an advantage in terms of chemical resistance, reduced protein adsorption or heat resistance.

[0005] These properties described above are met to some extent by membrane materials that can be mixed into the hydrophobic membrane material. A special step needs to be made hydrophilic so that these hydrophobic membranes can be easily wetted and used in the aforementioned filtration tubes. An example is the European patent EP0
571 871 B1, EP0 082 433 B1, EP0 228
No. 072 B1, EP245000 A3 and EP0186 758
B2.

[0006] Common to all efforts is the assurance of simple wetting of the membrane material, and is therefore intended to enable maintenance post-wetting testing of the filtration element. Nevertheless, despite the apparent hydrophilic nature of the membrane used in the finished filtration element, problems with the end cap material as a primary cause can occur with wetting. Various methods have been developed for the purpose of alleviating or eliminating problems caused by hydrophobicity or heat generated in the edge region.

[0007] EP 096 306 A2 discloses a special process for end sealing. For example, a hydrophilic membrane filter such as a nylon filter is sealed with a hot-sealable polyester film disposed on one side using a solventless polyethylene coating as a hot melt cement.

[0008] EP 03 27 025 B1 describes a porous filter in which the membrane structure is transferred into a film-like state on one side of the membrane, so that there are places that are impermeable to fluids. ing.

[0009] EP 00 36 315 B1 describes a method in which, in addition to the hot sealing method and also a mechanical method, the high reaction zone of the porous filtration membrane is treated by pouring glue.

[0010] World patent WO 95/14525 discloses a hydrophilic membrane modified and claimed in the present invention in terms of a method for partially hydrophilizing a high reaction zone of a porous membrane and its impregnation zone intended for embedding. That is, it discloses that the hydrophilic membrane should preferably be at least twice as hydrophilic in the untreated membrane area.

[0011] German Patent DE 296 20 189 U1 discloses that a porous membrane made hydrophilic is bonded (laminated) to a porous porous thermoplastic polymer fiber fabric at least at its ends.
It describes the complex method of being done.

Common to all of the foregoing methods is the need to treat the high reaction zone of the porous filter media required in multiple working steps before embedding of the membrane in the end cap. . However, this is associated with an increase in labor input and consequently very high costs.

The materials of the end caps are EP 0 096 306 A2, World Patent WO 95/14525, German Patent DE 296 20 189 U1,
In particular, it is disclosed in US Pat. No. 3,457,339.

In EP 0 096 306 A2 the following polymers are listed: That is, polyolefins (polyethylene, polypropylene, polybutylene, polyisobutylene), polyamide, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyester, polycarbonate, polymethacrylate, polyallyl, and polyoxymethylene. Polytetrafluoroethylene and polytrifluorofluoroethylene can be used as well. Polypropylene is preferably used for filtering biological fluids.

The patent WO 95/14525 furthermore refers to polysulfones and the German patent DE 296 20 189 U1 refers to polyether sulfones.

US Pat. No. 3,457,399 discloses polystyrene, cellulose acetate, ethylcellulose cellulose acetate butyrate, vinyl oxide, vinyl acetate copolymer, vinylidine chloride chlorodiphenyl copolymer, polyvinyl butyral, polytrifluorochloroethylene and Lists polymethyl methacrylate. The filter media can be the most variable material that can be combined with these end cap materials. It is common to all publications that only thermoplastic polymers are considered suitable for endcaps.

Conventionally, in order to produce a filter element, only a few millimeters of the filter media, for example the end of the membrane, have been completely melted or simply immersed in a superficially melted end cap. It is. As the membrane material is embedded in the endcap melt of the synthetic thermoplastic and the sealant subsequently solidifies, undesired changes in physical properties within and completely outside the mounting area can occur on the membrane.

For example, polyvinylidene difluoride, polysulfone, polyester sulfone or polytetrafluoroethylene do not settle in the above-mentioned end cap material without causing heat damage combined with the film.

When easy wettability of the filter element with water or aqueous solution is not required for the maintenance test (or wettable with an alcohol solution), or the glass transition temperature or melting point of the membrane material is the above-mentioned hydrophilic end cap. If the material is not suitable for use,
Polypropylene is always used. Therefore, these membrane-type polypropylenes with end-area defects need to be hydrophobized.

An object of the present invention is to devise a filter element in which the characteristics of the filter medium do not have an adverse effect by being embedded in the fixing element. This object is achieved by a fixing element comprising a hydrophilic thermoplastic elastomer at least in the buried area of the filter medium. In order to effectively embed the filter medium in the fixing element, for example, the end cap, it is important to monitor the melting point or glass transition humidity of the filter medium, the melting point of the end cap material, and the wettability of the end cap material. It starts with the research results.

The higher the melting point of the filter medium and the lower the temperature of the superficially melted material of the fixing element, the less adverse effects the material melt can have on the filter medium. On the contrary, the fixing elements need to have sufficient mechanical stability even at temperatures up to 145 ° C., since they are very often used repeatedly in the form of steam sterilization for the sterilization of filter media at a temperature of 145 ° C. . The filter media must not in any case be peeled from the set area by this method, but after cooling and moistening of the filter element, they must pass a maintenance test and be reliably set to ensure trouble-free aseptic filtration. Need to remain.

The thermoplastic elastomer used as claimed in the present invention retains a rubbery elastic state such that no deformation remains at low temperatures, enters a viscose state at a relatively high temperature, and resembles a thermoplastic resin. It is a polymer that can be processed into this state. This thermoplastic elastomer is exactly the same as a thermoplastic resin, and can be processed into a fixing element having the advantage of a relatively low melting point of 180 ° C. or less. Depending on the chemical structure, these materials have a pronounced hydrophilic character with a certain flexibility, which is particularly advantageous when a highly reactive membrane is embedded.

[0023] These properties are such that high foaming property and low glass transition temperature (hereinafter referred to as Tg)
), And a hard and crystalline segment with even lower foamability and a high Tg and also a tendency to crosslink. The soft and hard segments must be compatible with each other and exist as individual non-penetrating phases.

A key feature of these thermoplastic elements is the reversibly separable cross-linking site of thermal instability. Preferably, the melting point of the thermoplastic elastomer used is 5 ° C. to 50 ° C. lower than the melting point of the filter medium. This is possible by a corresponding adjustment of the proportion of the hard and soft segments. Preferably, the thermoplastic polymer is a polyether-polyamide block copolymer.

By varying the molecular mass ratio between the polyamide part and the polyethylene part, thermoplastic elastomers with different mechanical and chemical properties can be achieved as a result. The polyether-polyamide block copolymer has the following advantages.・ High mechanical properties ・ Good properties at low temperature ・ Good dynamic properties ・ Ease of processing ・ Narrow melting point affected by polyamide part

Using the examples of polyether block amides, it has been found that very good wetting and rewetting results are also achieved with these materials. Another advantage is that
As the two-phase structure (straight and positive chains of the hard polyamide segment and the soft polyether segment), different material forms having different melting points can be produced. All of these melting points are within the temperature range of 148 ° C. to 174 ° C., and are particularly preferable for embedding of a film material in a fixing element (ASTM method D2117), and therefore, these melting points have similar hydrophilic properties. It is much lower than the melting point of similar polyamide homopolymers or polybutylene terephthalate polymers.

Other preferred thermoplastic elastomers (abbreviated as TPE) are styrene-type resins, elastic alloys, polyurethane resins and polyetheresters with the characteristic components summarized in Table 1.

[0028]

[Table 1] Here, SBS, SIS, and SBC are styrene-triblock copolymers, TP-NR is thermoplastic natural rubber, and TP-NBR is thermoplastic butadiene acrylonitrile rubber.

When a thermoplastic elastomer is used, it is now possible to apply a film material having a particularly low melting point to a hydrophilic fixing element without having to perform a complicated additional step or treatment on its end. Printing can be performed without having to worry about adverse effects or loss of hydrophilic properties, or damage to the film due to extremely high printing temperatures.

Of course, in addition to the membrane, any other filter media can be fixed to the thermoplastic elastomer. As a result of having very similar melting points, it can be used as a substitute for polypropylene and, more particularly, can be used in applications where the highest possible hydrophilic properties are preferred for the end zones.

Another advantage is the possibility that the elements of the fusing element can be produced from different materials. Preferably, the members of the fixing element can be made of thermoplastic elastomers having different melting points.

Thus, the filter element chip can be produced from, for example, a polyether block amide material having a high set melting point. This mechanically most stressed part as a result of the high melting point has significant mechanical stability at high temperatures. Butt welding using a heat reflector is preferred, and the portion can contact the end cap of the low melting point copolymer. Thus, for example, it is possible to carefully embed the temperature-sensitive film material in the hydrophilic fixing material, and at the same time, at a relatively high temperature (105 to 145 ° C.), a filtration method suitable for performing a filtration operation involving repeated sterilization. Embedding became possible as a result of using special chip components made of the same material but having a relatively high melting point to produce the device.

In another preferred embodiment, the fusing element can be produced from any kind of polymer, for example PP, in which the buried area of the filter medium is coated with a thermoplastic elastomer.
Preferably, polysulfone, polyethersulfone, polyphenylsulfone, polytetrafluoroethylene, polyvinylidene fluoride, cellulose derivative, polyamide, aromatic polyamide, polyimide or polypropylene is used for the filtration element claimed in the present invention.

The filter medium is preferably a filter membrane having pores of preferably 0.01 to 10 microns, preferably 0.1 to 3 microns. The filter membrane includes one porous cloth as a support. The present invention will be described below using examples.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION

A pleated filtration tube with a membrane having a pore diameter of 0.2 microns and a membrane area of 0.7 m ² was produced, and both polysulfone and further polyethersulfone membranes were subjected to impression pressure and tested in various ways. Was. The membrane was fixed for comparison in polypropylene and polyether block amide endcaps. After wetting these filter tubes under the following conditions, each was measured for air diffusion at a pressure of 2.7 bar (
(Pressure holding test or maintenance test). a Wash with water at a pressure difference of 0.3 bar for at least 10 minutes b Wash with water at a pressure difference of 1.0 bar for at least 10 minutes c 10 at a pressure difference of 4.0 bar Washing with water at intervals of not less than min d Washing with water at intervals of not less than 10 minutes at a differential pressure of 0.3 bar and steam at intervals of not less than 20 minutes at an excess pressure of 0.5 bar Processing, then 0. Rewash with water at a pressure difference of 3 with an interval of 10 minutes or more

[0036]

【Example】

Example 1 A pleated polysulfone membrane was fixed in polypropylene and polyether block amide end caps and the wetting ability of the filtration element was checked.

[0037]

[Table 2]

Example 2 The filter element from Example 1 was washed with water at intervals of 20 minutes or more using a differential pressure of 0.2 bar, then dried at a temperature of 80 ° C. for 12 hours and rewet. Performance was checked.

[0039]

[Table 3]

Example 3 A pleated polyethersulfone membrane was anchored to polypropylene and polyether block amide endcaps. The pre-washed and dried filter element was then autoclaved up to 10 times in the dry state. The wetting capacity of the filter element was 1 at a maximum pressure of 0.3 bar of the element using an air diffusion measurement of 2.7 bar.
Inspection was performed after each autoclaving by washing with water at intervals of 0 minutes or more.

[0041]

[Table 4] Filtration tubes with polyether block amide endcaps show obvious wetting as well as rewet advantages. For example, even under dramatic conditions such as autoclaving a dry filter element, the rewetting capacity of the filter element is good and uniform.
An extremely low wetting pressure is selected to allow complete wetting of the device. This is in contrast to devices with polypropylene end caps that are not completely wet as the number of work cycles increases.

FIG. 1 shows a fixing element 1 including an end cap 3 and a chip 2. Fold filter media 6
Are embedded in the end cap 3 and are shown as a filter membrane 7 provided with a single porous cloth 8. The fixing element 1 is made of various materials. The end cap 3 is produced exclusively from a thermoplastic elastomer having a low melting point, while the tip 2 is produced from a thermoplastic elastomer having a high melting point. The tip 2 and the end cap 3 are joined to each other by butt welding with a heat reflector.

FIG. 2 shows that the fixing element 1 in the area 4 facing away from the filter medium 6 is made of polypropylene coated with a thermoplastic elastomer 5 in the embedded area of said filter medium 6.
Another embodiment is shown. If a similar melting point is followed, embedding can be facilitated by melting the material. The fact that the filter medium 6 is also embedded in the polypropylene material 4 has no effect on the hydrophilic properties of the filter medium, since the filter medium 6 in the transition range is embedded in the layer of the thermoplastic elastomer 5. The thickness of the layer 5 is, for example, 3 mm. Typical layer thicknesses range from 0.5 to 4 mm.

[Brief description of the drawings]

FIG. 1 and

FIG. 2 shows two end caps in cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing element 2 Chip 3 End cap 4 Area located away from filter medium 6 5 Thermoplastic elastomer 6 Filter medium 7 Filter membrane 8 1 body porous cloth

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] August 25, 2000 (2000.8.25)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 9

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction contents]

This is possible by corresponding adjustment of the proportion of the hard and soft segments. Preferably, the thermoplastic polymer is a polyether-polyamide block copolymer.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

By varying the molecular mass ratio between the polyamide part and the polyethylene part, thermoplastic elastomers with different mechanical and chemical properties can be achieved as a result. The polyether-polyamide block copolymer has the following advantages.・ High mechanical properties ・ Good properties at low temperature ・ Good dynamic properties ・ Ease of processing ・ Narrow melting point affected by polyamide part

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

Using the examples of polyether block amides, it has been found that very good wetting and rewetting results are also achieved with these materials. Another advantage is that
As the two-phase structure (straight and positive chains of the hard polyamide segment and the soft polyether segment), different material forms having different melting points can be produced. All of these melting points are in the temperature range from 148 ° C. to 174 ° C. and are particularly preferred for embedding the film material in the fixing element (ASTM method D2117) and therefore have similar hydrophilic properties with similar hydrophilic properties. Much lower than the melting point of polyamide homopolymer or polybutylene terephthalate polymer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 71/34 B01D 71/34 71/36 71/36 71/64 71/64 71/68 71/68 ( 81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW) , EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN , CU, CZ, D E, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Schneider. Georg Germany. De-55545. Bad. Kleznach. Hufershamer. Strase. 51 (72) Inventor Renner. Tiro Germany. De-55595. Mandel. Kruznasha. Strase. 17 F-term (reference) 4D006 GA01 JA22C JA27C MA02 MA09 MA22 MB09 MC11 MC23 MC29 MC30 MC54 MC62 MC63 [Continued] The thermoplastic polymer is a polyether-polyamide block copolymer.

Claims (9)

[Claims] 1. A filter element comprising a filter element of a hydrophilic polymer embedded in a fixing element, for example an end cap and / or an adapter, in particular a wound and / or pleated filter element, wherein said embedment element 1 is at least said filter element 6. A filter element comprising a hydrophilic thermoplastic elastomer in an embedding area of 6. 2. The filter element according to claim 1, wherein the melting point of the thermoplastic elastomer used is lower by 5 ° C. to 50 ° C. than the melting point of the filter medium. 3. The filter element according to claim 1, wherein the thermoplastic polymer is a polyether-polyamide block copolymer. 4. The filter element according to claim 1, wherein the thermoplastic elastomer is a butadiene-styrene block copolymer, a styrene resin, an elastic alloy, polyurethane or polyetherester. 5. The filtering element according to claim 1, wherein the members 2, 3 of the embedding element 1 are made of thermoplastic elastomers having different melting points. 6. The filter element according to claim 1, wherein said fixing element is made of a polymer coated with a thermoplastic elastomer in an embedded area of said filter medium. 7. The filter medium according to claim 1, wherein the filter medium is made of polysulfone, polyether sulfone, polyphenyl sulfone, polytetrafluoroethylene, cellulose derivative, polyvinylidene fluoride, polyamide, aromatic polyamide or polypropylene. 7. The filtration element according to any one of 6. 8. The filter element according to claim 1, wherein said filter medium is a filter membrane having a pore size of 0.01 to 10 microns. 9. The filter element according to claim 1, wherein the filter membrane 7 includes a one-piece porous cloth 8 as a holding body.