KR20010074723A - Filter element - Google Patents

Abstract

The present invention relates to a filter material of a hydrophilic polymer inserted into a fixing element such as an end cap and / or an adapter, in particular a filter element having a bent and / or pleated filter material.

Filter elements are known, whereby the properties of the filter material do not have a negative effect by insertion into the stationary element. The fixing element 1 in the region where the filter material 6 is inserted consists of a hydrophilic thermoplastic elastomer.

Description

Filter element {FILTER ELEMENT}

Porous filter materials are made of the most variable thermoplastic materials such as polypropylene, polyamides, aromatic polyamides, polyimides, polysulfones, polyether sulfones, cellulose derivatives, polyvinylidene fluorides, polytetrafluoroethylene.

Such filter membranes are also treated in the form of pleated or curved in the so-called membrane filter tubes which in most cases are inserted into the so-called end caps in the fixing element. US 3 457 339 describes a method of making such a filter material. Membrane filter tubes made using this or similar methods are characterized by being inspected after wetting with a suitable medium when the tube material is preserved, especially when the membrane material used has a pore size in the range of 0.04 to 5 microns.

In most applications, for wetting the membrane filter tubes, water or aqueous solutions are used. The more easily wetting of the filter elements becomes possible, the more hydrophilic components are used. For this reason, in most cases for the so-called sterile filtration of liquids, hydrophilic membrane materials are used, for example, polyamides or cellulose derivatives. Depending on the application and requirements for the membrane material, it is necessary to use other membrane materials that have advantages in terms of chemical resistance, reduced protein absorption or thermal resistance. This property is satisfied to some extent with membrane materials that can be included between hydrophilic membrane materials. This hydrophilic membrane must be hydrophilic in a particular process so that it is easily wetted and used in the filter tubes described above. Examples of this are known from EP 0 571 871 B1, EP 0 082 433 B1, EP 0 228 072 B1, EP 245 000 A3, EP 0 186 758 B2.

Since the purpose of ensuring simple wetting of the membrane material is common to all efforts, it becomes possible to inspect the filter elements after wetting for integrity. Finally, although the significant hydrophilicity of the membrane due to filter element problems occurs with wetting, it is the first of all that results in the end cap material.

Different processes have all been developed with the aim of mitigating or eliminating the problem of hydrophobicity or heat loss in the edge zone.

EP 096 306 A2 describes a special process of edge sealing. Hydrophilic membrane filters, such as, for example, nylon filters, are sealed with a hot sealing polyester film, which is provided on one side with a solvent-free polyethylene coating as hot melt cement.

EP 03 27 025 B1 describes a porous membrane filter having an impermeable position relative to the fluid as a result of moving the membrane structure to one side of the membrane in a film like state.

EP 00 36 315 B1 describes a process in which in addition to the hot sealing process and the mechanical process, sensitive areas of the porous filter membrane are treated with potting with an adhesive.

WO 95/14525 describes a partial hydrophilic process of a sensitive region of a porous membrane, and as claimed in the invention, a hydrophilic membrane that is modified in the implanted region to be inserted has at least twice as hydrophilic as in an untreated membrane region. It is preferable.

DE 296 20 189 U1 describes a complex process wherein at least the hydrophilic porous membrane in the edge cross section is bonded (laminated) to the porous planar structure of the thermoplastic polymer fibers.

Prior to inserting the membrane into the end cap, the need in one or more work steps to deal with sensitive areas of porous filter material is common to all of the processes described above. However, this is associated with increased labor and consequently very high costs.

Materials for end caps are described in EP 0 096 306 A2, WO 95/14525, DE 296 20 189 U1 and in particular US 3,457,339.

EP 0 096 306 A2 lists the following polymers: polyolefins (polyethylene, polypropylene, polybutylene, polyisobutylene), polyamide, polyvinyl fluoride, polyvinylidene fluoride, polyacrylonitrile, polyester, poly Carbonates, polymethacrylates, polyalyl and polyoxymethylene. Polytetrafluoroethylene and polytrifluorochloroethylene are likewise used. Polypropylene is used for filtration of biological fluids.

WO 95/14525 describes polysulfones and DE 296 20 189 U1 describes polyether sulfones.

US 3,457,339 describes polystyrene, cellulose acetate, ethyl cellulose, cellulose butyl acetate, vinyl fluoride, vinyl acetate interpolymers, vinylidene chloridephenyl fluorinated interpolymers, butyl polyvinyl, polytrifluorochloroethylene and polymethyl methacrylate do. The filter material may be the most variable material that can be combined with such end cap material.

Thermoplastic polymers are common in all applications that can be appropriately considered for end caps.

Conventionally, in order to produce a filter element, the ends of the filter material, such as membranes, for example, sink several millimeters in the end caps which are either fully melted or superficially melted. When the membrane material is inserted into the end cap fusion metal of the synthetic thermoplastic and then the sealing material solidifies, unwanted changes in physical properties within and outside the fixed area can occur on the membrane.

For example, a membrane composed of polyvinyl difluorinated, polysulfone, polyester sulfone or polytetrafluoroethylene cannot be fixed to the end cap material described above without mass heat loss occurring on the membrane.

For the purposes of integrated testing, when the easy wettability of the filter element with water or aqueous solution is not needed (wet with alcohol solution) or the glass transition temperature or the melting point of the membrane material is determined by the hydrophilic end cap material described above. When not allowed to use, polypropylene is always used. Thus, in this type of membrane, there is a need for polypropylene with the disadvantage of edge zone hydrophobicity.

The present invention relates to a filter material of a hydrophilic polymer inserted into a fixing element such as an end cap and / or an adapter, in particular a filter element having a bent and / or pleated filter material.

1 and 2 show two end caps in cross section.

It is an object of the present invention to devise a filter element, wherein the properties of the filter material do not have a negative effect by inserting it into the stationary element.

This object is achieved by a fixing element having at least a hydrophilic thermoplastic elastomer in the insertion region of the filter material.

The present invention is successful in inserting filter material in a fixing element, such as in an end cap, and it is important to examine the melting point or glass transition temperature of the filter material, the melting point of the end cap material and the wettability of the end cap material.

The higher the melting point of the filter material and the lower the temperature of the molten material on the outer surface of the fixing element, the smaller the possible counter temperature effect of the molten material on the filter material. On the other hand, since the temperature is repeatedly used very frequently in the form of steam sterilization which sterilizes the filter element, the fixing element must have sufficient mechanical stability at temperatures up to 145 ° C. The filter material should in no case be disrupted in the areas fixed by this process, but must be firmly fixed for integrated testing after cooling and wetting of the filter material and to ensure trouble-free sterile filtration.

The thermoplastic elastomers used as claimed in the present invention are polymers having a rubbery elastic state at low temperatures, in which they change into a viscous state at high temperatures without being deformed and can be treated in such a state as thermoplastic resins. Including the additional advantage of a melting point relatively lower than 180 ° C., such thermoplastic elastomers can be treated in a stationary element like thermoplastics. Depending on the chemical structure, these materials have significant hydrophilicity with some degree of flexibility. This is particularly advantageous when sensitive membrane material is inserted.

This property is at the same time achieved with flexible elastic segments having high expandability and low glass transition temperature (herein referred to as Tg) in the polymer as well as rigid crystal segments with low expandability and high Tg and show a tendency for crosslinking.

Flexible and rigid segments are incompatible with each other and should be represented by separate and non-permeable phases.

The main feature of these thermoplastic elements is their thermally labile and conductively separated crosslinked arrangements.

The melting point of the thermoplastic elastomer is preferably 5 ° C. to 50 ° C. lower than the melting point of the filter material. This is made possible by correspondingly adjusting the ratio of hard and flexible segments.

The thermoplastic polymer is preferably a polyether-polyamide block interpolymer.

By varying the molar mass ratio between the polyamide moiety and the polyether moiety, thermoplastic elastomers with different mechanical and chemical properties are produced.

Polyether-polyamide block interpolymers have the following advantages.

-High mechanical properties

-Good properties at low temperatures

-Good dynamic properties

-Ease of processing

Narrowly limited melting point affecting the polyamide moiety;

Using examples of polyether block amides, very good wetting and rewetting results are achieved with these materials. Another major advantage is that different material forms with different melting points can be produced as a result of the biphasic structure (linear and regular chains of solid polyamide segments and flexible polyether segments). These melting points are all within this temperature range of 148 ° C. to 174 ° C., which is particularly suitable for the membrane material in the stationary element (ASTM method D 2117), which is one of comparative polyamide homopolymers or polybutylene terephthalate polymers having comparative hydrophilicity. Much lower than the melting point.

Other preferred thermoplastic elastomers (abbreviated TPE) are styrene forms, elastomer mixtures, polyurethanes and polyether esters with characteristic components, which are summarized in the following table.

TPE Classification Yes (Commercial Name / Producer) Flexible Homopolymer Segments Styrene type SBS SISSEBS Kraton D / SelCaliflex TR / Selsolprene / Philipscranton / Cell Butadiene or isopreneethylenebutadiene Styrene Styrene Elastomer Blends EPDM / PPEVA / PVDCNBR / PP Reflexex / Bayer Santoprene / Monsanto Thermoplastic natural rubber / MRPRA al clean / de plush auras / Monsanto Crosslinked EPDM Crosslinked NR Ethylene Vinyl Acetate Crosslinked NBR Propylene Propylene Vinylidene Chloride Propylene Polyurethane Des Mopan / Bayer Estan / Goodrich Peretane / Uffizi Ester glycol or ether glycol Isocyanate Chain Lengtheners H Bond Polyetherester Anitrile / azko hytrel / Dupon Alkylene glycol Alkylene terephthalate

From here,

SBS, SIS, SBC Styrene-Triblock Interpolymers

TP-NR Thermoplastic Natural Rubber

TP-NBR thermoplastic acrylonitrile-butadiene rubber

For thermoplastic elastomers, especially sinking membrane materials with low melting points without complex additional processes and treatments at the edge cross-section into the hydrophilic fixing element without having to worry about adverse effects or loss of hydrophilicity or damage to the membrane due to excessively high sinking temperatures. It is possible.

In addition to the membrane, also other filter materials can be immobilized in thermoplastic elastomers as a result of very similar melting points, as they are used in polypropylene as a substitute, especially in such applications, where the maximum possible hydrophilicity is also desirable in the edge zone region.

Another advantage is the possibility of producing the components of the fixing element from different materials.

The components of the fixing element are preferably composed of thermoplastic elastomers of different melting points.

Thus, the filter element tip can be made of polyether block amide material, for example, having a melting point set high. The mechanically highest pressured part resulting in the high melting point has significant mechanical stability at high temperatures. By means of butt welding by a heat reflector, this part can be connected with the end cap of the low melt interpolymer. Thus, for example, it is possible to carefully insert a temperature sensitive membrane material into a hydrophilic fixation material and at the same time use a special tip portion of the same material with a high melting point to manufacture the filter element, resulting in a high temperature ( It is also suitable for a filtration operation with a sterilization repeated at 105 ° C.

Another preferred embodiment is for producing a fixing element from a polymer, for example PP, which is coated with a thermoplastic elastomer in the insertion region of the filter material.

For the filter element as claimed in the present invention, polysulfone, polyether sulfone, polyphenyl sulfone, polytetrafluoroethylene, polyvinylidene fluoride, cellulose derivative, polyamide, aromatic polyamide, polyimide or polypropylene It is preferred that filter material be used.

The filter material is preferably a filter membrane having a pore size of 0.01 to 10 microns, preferably 0.1 to 3 microns.

The filter membrane has an integrated porous structure as a support material.

The invention is illustrated using the following examples.

A pleated filter tube with a pore diameter of 0.2 micron and a membrane area of 0.7 m 2 is produced, and the two membranes of polysulfone as well as polyether sulfone are used for sinking and inspected by different processes. The membrane is secured to polypropylene and polyether block amide end caps for comparison. Wetting of these filter tubes is checked by air diffusion measurement (pressure retention test or integrated test) at a pressure of 2.7 bar respectively after wetting under the following conditions.

a overflow of water with a pressure difference of 0.3 bar over a 10 minute time interval

b Overflow water with a pressure difference of 1.0 bar over a 10 minute time interval

c Overflow water with a pressure differential of 4.0 bars over a 10 minute time interval

d Water vapor treatment at an overpressure of 0.5 bar over a 20 minute time interval by overflowing the water with a pressure difference of 0.3 bar over a 10 minute time interval and then overflowing the water with a pressure difference of 0.3 bar over a 10 minute time interval.

Example 1

The pleated polysulfone membrane is fixed to the polypropylene and polyether block amide end caps and the wetting capacity of the filter elements is checked.

8 Average value of measured air diffusion (mL / min) in the filter tube

Wetting conditions a b c d Polypropylene end caps > 200 > 200 50 12 Polyether Block Amide End Caps 13 11 10 10

Example 2

The filter element from Example 1 was flooded with water over a 20 minute time interval with a pressure difference of 0.2 bar, then dried at 80 ° C. for 12 hours and tested for rewetting capacity.

8 Average value of measured air diffusion (mL / min) in the filter tube

Wetting conditions a b c d Polypropylene end caps > 200 > 200 57 16 Polyether Block Amide End Caps 14 12 11 10

The pleated polyether sulfone membrane is secured to the polypropylene and polyether block amide end caps. Thus, the preflushed and dried filter element is automatically attached in a dry state up to 10 hours. The wetting capacity of the filter elements is inspected after each automatic attachment by flooding the elements with water at a maximum pressure of 0.3 bar over a 10 minute time interval using an air diffusion measurement of 2.7 bar.

8 Average value of measured air diffusion (mL / min) in the filter tube

Number of autoclaves Polypropylene end caps Polyether Block Amide End Caps 1x 14 11 2x 16 11 3x 19 10 4x 24 9 5x 35 11 6x 48 11 7x 60 11 8x > 200 10 9x > 200 10 10x > 200 9

Filter tubes equipped with polyether block amide end caps exhibit distinct wetting and rewetting advantages. Under conditions such as autoclaving of dry filter elements, the wetting capacity of the filter elements is good and constant. Very low wetting pressures can be chosen to fully wet the elements, while elements with polypropylene end caps are no longer wetted with an increase in the number of cycles.

1 shows a fastening element 1 with an end cap 3 and a tip 2. The pleated filter element 6 is shown as a filter membrane 7 with a porous fabric 8 inserted and integrated in the end cap 3. The fixing element 1 has a different material. The end cap 3 is made entirely of thermoplastic elastomer with a low melting point, while the tip 2 is made of thermoplastic elastomer with a high melting point. The tip 2 and the end cap 3 are joined to each other by welding back to the heating reflector.

2 shows another embodiment, wherein the fixing element 1 in the region 4 facing the filter material 6 consists of polypropylene, which is a thermoplastic elastomer in the insertion region of the filter material 6. Coated with (5). The insertion process can be easily performed by melting the material based on similar melting points. In addition, since the filter material 6 is inserted into the layer 5 of the thermoplastic elastomer in the transition region, the fact that the filter material 6 is inserted into the polypropylene material 4 does not affect the hydrophilicity of the filter material. The thickness of the layer 5 is for example 3 mm. Typical layer thicknesses range from 0.5 mm to 4 mm.

The filter element according to the present invention as described above does not adversely affect the properties of the filter material by inserting it into the stationary element, the higher the melting point of the filter material and the lower the temperature of the molten material on the outer surface of the stationary element The lower, the less likely the effect of the opposite temperature of the molten material on the filter material is, and since it is repeatedly used in the form of steam sterilization to sterilize the filter element, the fixing element has the effect of having sufficient mechanical stability at temperatures up to 145 ° C.

Claims (9)

In a filter material of a hydrophilic polymer inserted into a fixing element such as an end cap and / or an adapter, in particular a filter element having a curved and / or pleated filter material Filter element, characterized in that the fixing element (1) has at least a hydrophilic thermoplastic elastomer in the insertion region of the filter material (6). The method of claim 1, The melting point of the thermoplastic elastomer used is between 5 ° C. and 50 ° C., lower than the melting point of the filter material. The method according to claim 1 or 2, Said thermoplastic polymer being a polyether-polyamide block interpolymer. The method according to claim 1 or 2, The thermoplastic elastomer is a butadiene-styrene block interpolymer, a styrene form, an elastomer mixture, a polyurethane and a polyether ester. The method according to any one of claims 1 to 4, The component (2, 3) of the fixing element (1) is characterized in that it consists of thermoplastic elastomers of different melting points. The method according to any one of claims 1 to 4, The fixing element (1) is characterized in that it consists of a polymer coated with a thermoplastic elastomer (5) in the insertion region of the filter material (6). The method according to any one of claims 1 to 6, The filter material 6 is characterized in that it consists of polysulfone, polyether sulfone, polyphenyl sulfone, polytetrafluoroethylene, cellulose derivative, polyvinylidene fluoride, polyamide, aromatic polyamide, polyimide or polypropylene Filter element. The method according to any one of claims 1 to 7, The filter element (6), characterized in that the filter membrane (7) having a pore size of 0.01 to 10 microns. The method according to any one of claims 1 to 8, The filter element, characterized in that the filter membrane (7) has a porous structure (8) integrated as a support material.