DE2910289A1 - LEAF-SHAPED FILTER MEDIUM - Google Patents

Description

Patent attorneys Dipl.-Ing. H. ¥ ϊιοκμανγ :, Dipl.- Phys. Dr. K. Fincke

Dipl.-Ing. F. A. Weickmänn, Dipl.-Chem. B. Huber H / WE / LI Dr.Ing.H.L.SKA

8000 MUNICH 86, THE j? £ i "H fQ ~» Ü

PO Box 860 820

MÖHLSTRASSE 22, CALL NUMBER 98 39 2i / 22

I.S. # 14668 & 15108

AMF INCORPORATED, 777 Westchester Avenue, White Plains, N.Y. 10604

(V. St. A.)

Leaf-shaped pilter medium

description

The invention relates to filtration and, more particularly, to removal of submicron contaminants from aqueous systems using sheet filter media containing high levels of contain particulate filter aids.

Filtration of small particle size contaminants from liquids is carried out using various porous Filter media through which the contaminated liquid is passed. In order to act as a filter, the medium must pass through the Allow liquid, usually water, while retaining the particulate contaminants. The reluctance of the impurities is caused by one of the following two distinctly different filtration mechanisms: namely (1) the mechanical attraction and (2) the trapping of the particles by electrokinetic effects. With the mechanical Attraction, the particle is removed by physical trapping, when it tries to pass through a hole smaller than itself. In the case of electrokinetic trapping the particle collides with a surface in the porous filter medium and is caused by short-range attractive forces retained on the surface.

With the exception of microporous polymer membranes, the known porous filter medium, which are suitable for the filtration of finely divided impurities, made of fiber-fiber or Fiber-particle mixtures produced by vacuum entanglement from a aqueous slurry have been dynamically formed, whereupon the finished sheet has been dried. With such fibrous Filter media where the retention of particulate contaminants depends on mechanical attraction, It is necessary that the pore size of the filter medium is smaller than the particle size of the impurities that emerge from the liquid should be removed. For the removal of submicron fine contaminant particles the fiI-

0 30039/0222

terinedium therefore have correspondingly fine pores. Because the pore size of such leaves mainly on size and morphology Of the materials used to form the sheet is determined, it is necessary that one or more of the component materials have a very small size, for example fibers with a small diameter are {cf. for this e.g. üS-PSen 3 158 532, 3 238 056, 3 246 767, 3 353 682 and 3 573 158).

When the size of the impurities to be removed by filtration decreases, and particularly enters the submicron range, then the difficulty and cost increase in order to properly sized Preserve fiber structures for optimal filtration through mechanical attraction. There is therefore considerable interest in the use of fine, particulate matter, for example of diatomaceous earth.

With such materials, however, it is necessary to provide a matrix, to have a coherent, manageable structure for commercial and technical purposes. Therefore, at least one of the component materials is of the leaf has a long, self-binding structural fiber to give the leaf sufficient structural integrity in both the wet state, as formed, as well as in the final dried state to impart handling during treatment and suitability for the intended purpose. Unrefined Cellulose fibers, such as from wood pulp, cotton, cellulose acetate or rayon, are commonly used. These fibers are typically relatively large, with commercial diameters in the range from 6 to 60 μm. Wood pulp that very often Used because of its low cost, has fiber diameters that go from 15 to 25 μm and fiber lengths from about 0.85 to about 6.5 mm.

Sheet-shaped filter media or sheets are made from a filter medium usually by vacuum entangling the component material formed from an aqueous slurry. The vacuum felting is placed on a perforated surface, usually a wire mesh, that in practice, vary from 50 mesh to 200 mesh

30-Q3-9 / 0222

V-

can, whereby the mesh openings can go from 280 μΐη to 70 μΐη, carried out. Finer meshes are due to clogging problems and / or structural defects unsuitable.

The size of the openings in the holey vacuum entanglement surface and the pore size of the cellulosic fiber matrix of the sheet formed are compared to some or all of the dimensions of the fine fibers or particulate components necessary to produce the desired submicron filter media sheets great. The retention of such fine components during vacuum formation of filter media sheets is difficult and dictates the selection of such materials, the specific details of the process of forming the filter media sheets and, most importantly, what the extent to which the filtration behavior can be achieved has severe limitations. Fine fibers, their length compared to their diameter can be large, pose fewer problems, and are reasonably well restrained. On the other hand, they tend to be fine, particulate Materials during sheet formation tend to show very poor reluctance.

Flocculation with polymeric retention agents or coagulation has been used as a measure to improve the retention of fine particulate materials to cause the agglomeration of particles to form an effective large size is obtained. A filter sheet made from a well flocculated Slurry has been prepared, however, has one broad particle size distribution, with small pores in the flakes occur and large pores occur between the flakes. The presence these larger pores limit the ability of the filter sheets to remove fine impurities ζλι. Using a Flocculation to obtain high retention in the filter medium is therefore somewhat unproductive.

It is naturally possible to apply hydrodynamic shear forces _r break up the flakes, and further Ladungsmcsdif izierungen make the system to a stable, dispersed form adopted. As a result, a relatively uniform sheet with a narrow pore size distribution is obtained. The retention of the parts

moderate materials in such a system is very low what leads to a concomitant reduction in the filtration performance.

In addition to controlling dispersion properties (and therefore the porosity of the sheet) and to maintain wet strength, charge modifiers are used to reduce the zeta potential control of leaf constituents and behavior in electrokinetic trapping of lightly charged contaminants to bring it to a maximum value. In practice they will be cationic Charge modifiers are used because most naturally occurring contaminant surfaces are at liquid pH are of practical interest anionic. A preferred charge diffusion agent is a melamine formaldehyde colloid, that is described for filter sheets in U.S. Patents 4,007,113 and 4,007.

In general, filter media in which charge-modified Items used are inserted without further treatment after the formation of the media. However, when a treatment for biological fluids is provided, then the filter media are usually germ removal or sterilization measures under severe conditions, e.g. relatively high temperatures and pressing, subjected. These conditions may reduce the behavior of various charge-modified ones to some extent Cause media or increase the content of extractables beyond permissible limits. Although this If the phenomenon has not yet been fully elucidated, it can be assumed that it is due to a loss or degradation of the Resin itself or the charge functionality of the system is due to physical or chemical effects. In in each case it appears to be specific to the selection of the resin. In particular, the one modified with melamine-formaldehyde colloid System unable to satisfactorily withstand autoclave or hot water purging conditions, creating significant Amounts of charge are lost and thus the effective service life is limited. This charge modifier, the low one Molecular weight is also in terms of the extent of

available charge modification is limited. Substitutes for this Meeting limitations is of particular interest.

The object of the invention is therefore to provide charge-modified, sheet-like Filter media with increased filtration performance, especially for the highly effective removal of submicron contaminants from aqueous Systems available.

The invention is also intended to provide a sheet-shaped filter medium which is high in fine particulate matter content.

The invention is also intended to provide a filter medium that is sterile made or sterilized can be provided which is resistant to degradation upon such treatment and that maintains a sufficient charge potential to increase electrokinetic trapping of lightly charged impurities to effect.

According to the invention, charge-modified, sheet-shaped filter media are used manufactured by using a fiber system for the self-binding media matrix during sheet formation, the whipped Cellulosic fibers, usually a moderately to highly whipped pulp, that a fiber system with a Canadian standard freedom (Canadian Standard Freeness) of 100 to 600 ml, preferably 200 to 300 ml or less, is obtained. The provision of shorter or more fibrillated fibers allow retention of fine, particulate materials in preferred embodiments from 50% up to 70% or more based on that Weight of the sheet.

The charge modifier that is selective for / lie manufacture of the filter media that are to be made sterile or sterilized is a cationic polyamido-polyaminepichlorohydrinharζ, which resists degradation in such treatment ^ and a maintains sufficient positive charge potential that an increased

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Gertes electrokinetic capture of small, negatively charged impurities is effected. Sterilizable filter media can thus be formed which are non-toxic, contain less than 1.5% extractables and which are effective in use, despite being ^{under autoclave conditions of, for example, 130 °} C. under a pressure of 6.8 kg for 1 hour or a hot water rinse flow of 82 ° C for 1 hour at a flow rate of 225 ccm / min, surprisingly, such filter media also show a considerably improved behavior in the filtration of liquids with an intermediate pH value (5-8) to high pH compared to a cationic melamine formaldehyde colloid charge-modified system.

The sheet-shaped filter medium, which is preferably made by vacuum entangling a cationically disperse, aqueous slurry of whipped or ground cellulose fibers and fine, particulate materials, shows a uniform, high Porosity and a fine pore size structure with excellent Filtration and flow properties.

It should be noted that the high retentions of particulate Substances that can be obtained according to the invention are to be regarded as significant when the total amount of cellulose fibers that acts as a matrix. Thus, with preferred Embodiments the cellulose pulp only as little as 10 make up to 20% of the total sheet weight.

Relatively high particulate retentions (up to about 45% by weight) have been obtained in the filtration technique, but only at the expense of an unacceptably high pressure drop due to the tight construction used. In contrast, the sheet filter media of the present invention can be constructed in such a way that, even at a 70% load, it ^{exhibits only low differential pressure drops, e.g., less than 0.28 kg / cm 2} (4.0 psid).

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Combinations of fibers of different dimensions for filters are already known and are described, for example, in U.S. Patents 2,144,781, 2,372,437, 2,708,982 and 3,034,981. The retention of ion exchange resins is related to pulp freedom in U.S. Patent 2,955,067.

The invention is explained in more detail in the drawings. Show it:

Figure 1 is a graph of normalized streaming potential versus the time in which equilibrium flushing curves for a known filter sheet and a filter sheet according to the invention are compared with one another will;

FIGS. 2 and 3 are graphs of the normalized streaming potential and the turbidity of the effluent as a function of time in the provocation test of monodisperse latex contamination in a known filter sheet and a filter sheet according to the invention with one another to be compared;

Figure 4 is a graph of normalized streaming potential versus time in the equilibrium washout curves of a known filter sheet with a filter sheet according to the invention in untreated Form, autoclaved form and form rinsed with hot water.

The sheet filter media of the present invention are made from cationic modified filter elements produced, which are usually in the form of cationically disperse, aqueous slurries, the cellulose fibers and optimalized contents of fine, particulate Materials such as diatomaceous earth or perlite contain. The filter elements can be in the slurry and in the dynamic cationic sheet made by vacuum entangling and drying be modified or the filter elements can be pretreated and closed Filter sheets are deformed. A specific feature of the invention is the provision of filter media sheets in which the Content of retained particulate material is increased compared to a conventionally produced sheet.

The refinement state of a wood pulp fiber is determined by means of a "Freedom Tests", where the rate of flow through a forming pad of the fibers on a standard screen is determined. The "Canadian Standard Freeness Tester" is used most frequently. With this method, the volume of water (expressed in ml) measured overflowing from a receptacle which has an opening outlet at the bottom. The Canadian Standard Freedom measurements are provided herein used. Coarse, unbeaten wood pulp fibers result in high run-off speeds into the receptacle of the sieve, which leads to large overflow volumes and therefore gives a high degree of freedom. Typical wood pulps show values for the Canadian standard freedom of +400 ml to +800 ml. In the manufacture of paper or filter media Such pulps can be subjected to mechanical refining processes, for example beating or grinding 'whereby the cellulose fibers are cut and / or fibrillated. Such beaten fibers have lower ones Run speeds and therefore lower freedom values.

According to the invention, such a whipped pulp is used in the self-binding matrix of the filter media. The Canadian standard freedom of the pulp system varies according to the choice of pulp and it can indicate the various states of division or refining, for example when different pulps or differently beaten pulps are used for sheet formation. The beaten pulp is used, however, so that a composite or average value is obtained ml of usually 100 to 600 where lower values, for example, be 200-300 ml or less _r preferably represents a higher solids retention.

The wood pulp can comprise as little as TO% by weight, with up to to 20 to 30 wt.% of the total amount is preferred to one media sheet to obtain that has structural properties that are suitable for technical filtration purposes.

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The behavior is improved by reducing the amount of the fine, particulate Material in the sheet-shaped filter medium is maximized. While only as little as 10% fine, particulate matter a noticeable improvement in the filtration behavior Media type, optimal behavior is obtained if one the maximum amount of fine particulate material used. For technical filtration, the structural properties place one practicable maximum amount of about 70% by weight close. Slightly higher levels are possible for less demanding applications. In general, levels of 50-70% by weight are used.

There are different types of fine, anionic, particulate materials which are suitable for the intended purpose, e.g. diatomaceous earth, perlite, talc, silica gel, polymeric particulate materials, e.g. produced by emulsion or suspension polymerization, such as polystyrene, polyacrylates, polyvinyl acetate, polyethylene ( or other such materials as described in Emulsions and Emulsion Technology, Lissant, Kenneth J., Marcel Dekker, 1974), activated carbon, molecular sieves, clay etc. Functionally, the fine, particulate materials should have a specific surface area of more than 1 m ² / g and / or have particle diameters of less than 10 μm. In the broad sense, any fine particulate material may be suitable (such as JMFilter CeI, Standard Super CeI, Celite 512, Hydro Super CeI, Speed Plus and Speedflow; Dicalite 215 and Dicalite 416 and Dicalite 436). The evaluation can be done by known techniques. From a size, morphology, cost, fluid compatibility, and general behavior standpoint, finer grades of diatomaceous earth and perlite filter aid with an average particle size of less than 5 μm are preferred. In many cases, blends of several types of fine particulate materials, such as diatomaceous earth and perlite, in a weight ratio of about 80/20 to 20/80 will give better filtration performance or cost / performance comparison than can be achieved by using a single type. In a similar way, mixtures in all proportions of relatively coarse and fine, particle-conveying

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moderate materials, e.g., 50/50 parts by weight of particulate materials 10 and 5 µm in diameter can be used.

Suitable cationic polyamido-polyamine epichlorohydrin resins are

for example in the US-PSs 2 926 116, 2 926 154, 3 224 986,

3,332,901 and 3,382,096. You can be made by it

be that a dicarboxylic acid with a polyamine dip-

Ren reacted to produce a water-soluble polymer that with

Epichlorohydrin is further implemented. The dimer units can be the

general formula

) ₂ -KH / - (CH ₂ ) ₂ -

where χ is an integer from 1 to 7. The dicarboxylic acid can be aromatic or aliphatic. Examples are adipic acid, azelaic acid, diglycolic acid, oxalic acid and malonic acid. The cationic charge is induced by the amine function in a tertiary or quaternized configuration. Other suitable charge modifying resins which include a heterocyclic dicarboxylic acid
has been used as the starting substance are described, for example, in US Pat. No. 3,761,350. The cationic polyamido-polyamine-epichlorohydrin resins are commercially available, for example, as Polycup 1884, 2002 or S2064 (Hercules); Cascamide Resin pR-420 (Borden) or Nopcobond 35 (Nopco) available.

In papermaking, where cationic charge modifiers are sometimes used, the goal is to reduce the charge to about the isoelectric point in order to maximize the efficiency of entangling the fibers. In the case of filtration, a maximum charge is desired in order to remove the charged
Increase particles through electrokinetic mechanisms. In the present case, the surface charge of at least one of the negatively charged filter elements, ie the cellulose, or the particulate material is reduced, whereby the surface is less
is made electronegative. Optionally (and preferably) the charge is reversed by adding sufficient cationic charge modifier

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ORJGfNAL INSPECTED

-AS-

agent is deposited to make the surface electropositive to make, whereby at least certain electropositive areas or locations ii the filter sheet are obtained. In order to bring about a reversal of the charge, one normally goes through the isoelectric Point through. A positive charge is then established up to the maximum practical value.

The amount of charge modifier used in the present invention is thus preferably that which is sufficient that at least one cationically disperse system is obtained, i.e. a system in which there is no visible flocculation at ambient conditions in the absence of applied hydrodynamic Shear forces takes place. The system therefore contains essentially discrete fiber / particulate material elements that have a positive Have charge or zeta potential and are relatively uniform or are homogeneously distributed in and through the aqueous medium. The specific value naturally varies depending on the system and modifier selected. In individual cases, however, the amount can be guided by some orientation Preliminary tests are determined. For example, the turning point of a curve depends on the retention of particulate matter on the amount of charge modifier to the minimum Value for better behavior. A content of 2% is therefore suitable for a polyamido-polyamine-epichlorohydrin resin. Although further modifying agent used advantageously If so desired, this value represents the fixed balance on a cost performance basis. Pre-modified Filter elements, e.g., particulate material that has been precoated with the charge modifier, can of course can be incorporated into the filter sheets in any manner with similar results. If one is cationic disperse slurry is not used then charge modification is used decreased by controlling the levels of the modifier.

The charge modification effected can be determined by measurements of the zeta surface potential and through an improved filtration line

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performance for negatively charged particles in liquid systems demonstrated will.

The slurry of the pulp and particulate material is formed in any way. The order of adding these components to water to make the initial slurry form seems to be relatively unimportant. The consistency of the slurry is that necessary for a practical suspension of the components is the highest possible and amounts to about 4%. The system is hydrodynamic shear forces, for example by a paddle mixer, whereupon the charge modifier is added to the slurry.

The amount of shear is not critical; i.e. any other suitable shear rate or shear stress in view of the available facility, preferred treatment time, etc., can be applied. However, the amount of shear is simply selected and applied to break up the flakes and the system is kept in a dispersed state during the treatment. Education is natural a cationic disperse slurry the system from floc formation even in the absence of applied shear free.

After the charge modification, the slurry is further processed Water to the correct consistency required for vacuum entangling sheet formation, usually 0.5 to 2.5%, depending on the type of device used to form the sheet is used, diluted in a known manner. The slurry is formed into a sheet and baked in the usual manner dried. The behavior of the leaf is related to the drying parameters. Optimal conditions can be energy considerations or reflect the course of the thermal treatment, with unnecessary exposure to elevated temperatures is minimized, especially when approaching the point of decomposition or scorching of the system.

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- te--

According to a preferred embodiment of the invention, sheet-like Filter media composed of filter elements, i.e. a particulate material and a self-binding matrix of cellulose pulp, at least one of which has been charge modified, and wherein the pulp contains whipped pulp that a Canadian standard freedom of up to 600 ml, preferably less than 300 ml, e.g. 100-200 ml. The charge modifier consists of a cationic polyamido-polyamine epichlorohydrin resin and indeed an amount is used to reduce the electronegativity of the surface, preferably in an amount that a charge reversal beyond the isoelectric point is also obtained, for example, an addition amount of about 2 wt.%. Sheet-shaped filter media treated in this way can be used in the autoclave treated, rinsed with hot water or otherwise treated at elevated temperatures in order to reduce the temperature Sterilize or sterilize the structure. In addition to having a special suitability for the filtration of biological Liquids, these sheets can also be used for filtration without a rinse-off delay, as in Ions present in the structure have been removed during sterilization or disinfection. ,. -.

The advantages of the cationic polyamido-polyamine epichlorohydrin resin can be seen dramatically from the drawings. These represent the results of the tests according to Examples 6 and 7. The resin used in the present invention maintains a high charge and removal capacity, and it has a longer effective life Lifespan than the cationic melamine formaldehyde colloid of U.S. Patent 4 007 113.

The sheet-shaped filter media can be subjected to standardized tests such as the following:

Filtration performance test

In this test, a contaminated liquid with a specific Turbidity through the test filter with a constant vacuum

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drawn under standard conditions. The turbidity of the effluent is measured (using a Hach model 21OOA turbidimeter)
and as percent filtration efficiency compared to inlet haze calculated as

_T. , Inlet haze-outlet haze performance =

expressed. The test contamination is Hyplar (manufactured by Grumbacher), namely, a polydisperse acrylic latex made by emulsion polymerization containing colloidal polymer particles with 0/05 to 1.0 μΐη. The impurity content is 25-200 NTU (Nephelometric turbidity units) in distilled water a pH of 6.5 - 7.0. The filter sheet is cut into disks with a diameter of 57 mm and then placed in a vacuum filter holder, Millipore 47. 100 ml of the impurity dispersion produced in this way are then passed through the disk under Filtered using a vacuum of 58.4 cm Hg.

Membrane protection test

In this test, the contaminated liquid is pumped under standard conditions through the test filter medium and a membrane in series at a constant flow rate and the differential pressure is recorded over time. The time or the total volume of the liquid that flows through at a defined pressure increase is a measure of the service life of the prefilter
and it is satisfactorily related to usage behavior. Typically a 47 mm 0.22 μm membrane is used with a flow rate of. 225 ml / min. The test impurity is., The same polydisperse acrylic latex as
described above (Hyplar). The content of the impurity is
5-50 NTU (Hach Turbidimeter Model 2100A). The test is continued until the differential pressure across either the membrane or the test filter exceeds 0.35-0.70 kg / cm ² . Membrane protection times of less than a few minutes indicate no practical effect.

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Test of the oil flow

As a measure of the porosity of the filter media sheets, 100 SSU oil is pumped through the sheet sample until a differential pressure drop of 0.35 kg / cm ^{2 is} obtained. At this point the flow rate (ml / min) is recorded.

Normalized streaming potential

The measurement of the streaming potential is a conventional method for determining the zeta potential _r ie the electrical potential in excess over the surface and the surrounding liquid to the hydrodynamic shear plane over the mass potential of the liquid. In this test, the streaming potential values are determined and normalized for different pressure drops in the tested media, the results being given as units of mV / 0.3 m of water. The filter medium is evaluated by rinsing the filter medium with water until the measured streaming potential has a relatively stable, maximum value, at which point the filter medium has stopped releasing a significant ion species into the water, i.e. the inlet resistance equals the outlet resistance.

The test cell for the filter medium is based on the design by Oulman et al. JAWWA 56: 915 (1964). It consists of Lucite with an effective area of 20.3 cm ² (diameter 5.1 cm) and it is provided with carbon black electrodes. Water and mercury gauges are used to measure the pressure drop across the test medium. The values of the streaming potential (which by convention have opposite signs as the zeta potential and the surface charge) are measured with a high-impedance voltmeter. The inflow and outflow resistance are monitored with conductivity flow cells (cell constant = 0.02 / cm) using a resistance bridge.

After an equilibrium streaming potential has been established (i.e., after being flushed out), contamination challenge tests can be performed

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can be carried out in the same system using an aqueous dispersion of a monodisperse latex of a single size where the 90 ° light scattering intensity (selected for a high sensitivity for particle diameters in the range from 0.1 to 1.0 μια) of the inflow and the outflow can be measured, whereby a quantitative determination of the filtration performance of the filter medium is obtained. The turbidity of the effluent is under Measured using a Moniteck opacimeter. The entrance exam is selected so that it is in the range from 15 to 20 NTU, with a Dow diagnostic emulsion with 0.109 μm from a polymerized polystyrene / stex dispersion and the flow rate is kept relatively constant. The above tests will be more detailed in a lecture at 71st Annual AICHE Meeting (1978): "Measuring the Electrokinetic Properties of Charged Filter Media" Knight et al.

In the examples below, all proportions are based on total weight of pulp and particulate! Material based on exclusion of the charge modifier.

example 1

A number of filter sheets were made, with Weyerhauser Coho Kraft pulp was used which had been whipped to the stated values. Furthermore, Grefco Dicalite 416 Perlite used with an average particle size of 3.9 μια .

A charge modifier was used in these experiments cationic polyamine-polyamide epichlorohydrin resin (Hercules Polycup 1884; about 100,000 mole weight, particle size about 15oS) is used.

The total addition amount (on a dry basis) of the component materials was 80 g excluding the charge modifier. One constant proportion of the pulp (30 wt.% or 24 g) and the particulate material (70 wt.% or 56 g) was maintained.

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keep. The components were added to water in a 1 liter polyethylene jar given with vigorous stirring, creating an aqueous slurry with a consistency of 2%. The charge modifier was then added (the system became hydrodynamic Shear effect by means of a Hei-Dolph stirrer (PoIyscience Inc.) with four propeller blades rotating at about 700 rpm on setting 2). The slurry was then diluted to a consistency of 0.5% and made into a sheet with a thickness of about 0.41 to 0.51 cm (depending on the retention) vacuum entangled. This was done in a handsheet device measuring 23 cm by 30 cm using a 100 mesh screen Sheet was then removed, dried in a static oven at 177 ° C to constant weight. The final weight was then recorded. The comparison of the final weight of the sheet with all of the material added allowed total solids trapped in the sheet to be determined. The filter sheets were filtration (membrane protection) and oil flow tests, as described above, subject. The results are shown in Table I. . -

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Table I.

O C *> O O

co 'S, O NJ Ni N>

sheet Pulp salary Oil flow Membrane protection test Time
(min) (25 NTU) Membrane ^
P (kg / cm ² ) Solid No. freedom
(CSF) d.Charge
modified with
tels (wt.%) (ml / min) At first-
^ P (kg / cm ² ) 95 PillowAA
P (kg / cm ² ) 0.35 retention
(%) 1 660 2 105 0.08 104 0.04 0.35 73.8 2 660 2 - 0.05 14th 0.13 0.35 74.5 3 660 2 135 0.06 137 0.08 0.35 88.5 4th 520 2 53 0.1 136 0.09 0.35 86.1 5. 520 2 - 0.1 r * O 0.1 0.35 86.9 6th 52 θ ' 0 67 0.07 128 0.1 0.35 82.1 7th 400 2 43 0.1 129 0.01 0.35 86.1 8th 400 2 - 0.1 0.04 0.35 86.9 9 400 0 111 0.08 133 - 0.35 90.3 10 320 2 40 0.1 131 0.07 0.35 87.2 11 320 2 - 0.1 5 0.1 0.35 12th 320 0 98 0.02 143 0.1 0.33 91, 3 13th 200 2 26th 0.1 137 0.35 0.35 88.2 14th 200 2 - 0.1 4th 0.1 0.35 92.4 15th 200 0 58 0.07 111 0.007 0.04 91, 6 16 110 2 22nd 0.2 92 0.7 0.02 91, 6 17th 110 2 - 0.2 0.7 93.0 18th 110 0 not ff f ~ i 4 ™ f "" tc * 4 ™ r * t * l · "

- I.

CO

O KJ OO CO

From the above test values it can be seen that samples that did not had been charge modified, essentially no membrane protection showed. The solids retention improved with a decreased one average CSF value of the pulp system used. A failure of the systems with the lowest freedom occurred through Pillow clogging with a small increase in diaphragm pressure drop.

Example 2

A number of experiments were carried out according to Example 1, wherein as a particulate material Grefco Perlite 426 with an average particle size of 4.2 μπι and a constant Content (2%) of charge modifier (Hercules 1884) used became. The results are shown in Table II.

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-ZH

H OJ Xt

(ΰ E. in in in in Ln - O LO CM CTi CM , - M. υ ro ro ro ro ro ro ro O CM CM CM S. cn O O O σ O * - O O O O ω S. ft " 5 * <7 Egg <\ -a 23 . , Γ [^ in tn in CJ Ο O ro ro ro ro ro in tn LO CM cu S. O O O O O CM O ro ro ro co
M. ü O O O O O O O O O •H + J * ^ M. co
cu - r-- 4Y + J
•H pi O O tn tn O in CM O OO tn N CU ro in m ro ro τ— * ~ I 1 In) I Ü I. G_ CQ
ft W. Q
ro Cn pi Γ cn CM Xi CS S. O Ο O τ- τ- CM O CM CM CM S. IH υ O O O Ο Ο O O O O Φ G in} Cn ^. (Ti VO t— [^. O co CM ro CM co approx ■ Η in VO ro ro CM CM ί— rH "" ^ ** u-i I. ■ H O :O I dP to ■ μ • Cn • Η & CM CJ g cu CM CM CM CM CM CM CM CM CM -J • Ü -μ ■ Ö i-H td • H m ft! M-Jr-I + J ■ H CU Φ ■ H • Ö.P O 0) CM X! co oo τ— ^ - O VO CM CM CM CM CM ro VO CM CM I. 0) CM CM τ— Q) fa a M-I cn \ U ft • in -P (Ti σ τ - CM CM VO Γ- OO -μ CM CM CM CM CM CM CM (β H CO

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Example 3

A. Particulate filter aid was in an aqueous slurry at a consistency of 2.5% with the. given above
Held by charge modifier Hercules in 1884 over a
Pre-coated, insulated, drained and dried for 30 minutes at 121 ° C. for a contact time of about 15 minutes.

The treated particulate filter material was slurried in 100 ml of water and filtered through a porous fritted glass holder base into a vacuum filter holder, Millipore 47 mm, until on
Cake 0.64 cm thick had been formed. Filtration performance tests were then carried out. The results are shown in Table III.

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Table III

σ ο co co ¹ X. O NJ INJ

sample Type of part Salary of the La- ] Inlet door
exercise (NTU) Performance test power
(%) No. small-shaped
Materials application modification
agent
(Wt.%) 200 Outlet door
exercise (NTU) 75.0 29 DE 215 ¹ 0 200 50 97.8 30th DE 215 1 200 4.4 98.6 31 DE 215 2 - 2.8 - 32 DE 215 4th 200 - 50.00 33 PERLITE 416 0 200 100 99.50 34 PERLITE 416 1 200 0.3 98.90 35 PERLITE 416 2 200 1.2 98.85 36 PERLITE 416 4th 50 0.85 10.00 37 PERLITE 4106 ² 0 50 45.0 99.40 38 PERLITE 4106 1 50 1.0 97.60 39 PERLITE 4106 2 50 2.2 98.30 40 PERLITE 4106 4th 2.3

DE 215 is Grefco Dicalite calcined diatomaceous earth with an average Particle size of 2.7 μm

Perlite 4106 is Grefco Dicalite with an average particle size of

10 μια

ro to

N> OO CD

■ η-

The improvement of the filtration behavior with the charge modification is particularly dramatic with larger, particulate materials.

Example 3

B. An aqueous slurry of the precoated as prepared above, particulate material was alternatively formed into a filter sheet using 30% by weight of whipped pulp as a matrix contained. It was dried. The pulp system used had a freedom value of 130 CSF. There were membrane protection tests carried out, the results of which are summarized in Table IV.

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Table IV

sheet Pulp free Salary of oil flow Membrane protection test (25NTU) Time
(min) Pillow ./ \
P (kg / cm ² ) Membrane./!.!
P (kg / cm ² ) Solid No. unity (CSP) Cargo mode
difiziergs.-
average (wt.%) (ml / min) .'Inception Skis-
senA P (kg /
on ² ). 1 0 0.7 retention
(%) 41 416 PERLITE 0 21st 1.4 31.5 0.6 0.07 89.3 42 416 PERLITE 2 63 0.2 0 0 0.7 94.0 43 4106 PERLITE 0 262 0.04 8.3 0 0.35 - 44 4106 PERLITE 2 260 0.04 -

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Example 3

C. A preformed sheet containing 130 CSF pulp system (30 wt%) and Perlite 416 particulate was treated with Hercules 1884 resin (2% solids), dried and cured. In the filtration tests, the membrane protection time was 6.5 minutes and failure was due to bed clogging at 0.35 kg / cm ² .

Example 4

A. As in Example 3 A, mechanically defibered cellulose (Solka Floc) was precoated with cationic resin (Hercules 1884), dried and hardened. It was shaped into a filter cake and tested for filtration performance. The received Results are shown in Table V.

030039/0222

Table V

sample Type of part Salary of the La- Performance test Outlet door
exercise (NTU) power
(%) No. small-shaped
Materials application modification
agent ■
(Wt.%) Inlet door
exercise (NTU) 18th 28.0 45 Solka-Floc BW-20 0 25th 2.6 89.6 46 Solka-Floc BW-20 1 25th 2.4 90.4 47 Solka-Floc BW-20 4th 25th 19th 24.0 48 Solka-Floc BW-200 0 25th 0.43 98.3 49 Solka-Floc BW-200 1 25th 0.97 96.1 50 Solka-Floc BW-200 4th 25th

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Example 4

B. A filter sheet was made from a 30% untreated slurry Cellulose pulp and 70% pretreated, defibered cellulose formed according to Example 4 A and tested as in Example III B. The results obtained are shown in Table VI.

030039/0222

Table VI

sample Type of part Salary of Aafangskis-
sen ^ P
(kg / cm ² ) Membrane protection ( PillowM
P (kg / cm ² ) 5 NTU) No. small-shaped
Materials Cargo mode
dif.Mitt.
(Wt.%) 0.035 Time
(min) 0 Membrane /] ^
P (kg / cm ² ") 51 Solka-Floc BW-20 0 0.1 1.75 0 0.7 52 Solka-Floc BW-20 4th 0.035 6.50 0 0.35 53 Solka-Floc BW-200 0 0.035 2.75 0 0.7 54 Solka-Floc BW-200 4th 8.50 0.35

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Example 5

Filter media were produced as in Example 1, with 70%
particulate material and 30% pulp were used. As
particulate material was used diatomaceous earth (Grefco Dicalite 215). The system was made with 2% cationic resin
(Hercules Polycup 1884) surface modified. The pulp system was varied to reflect the presence of more heavily whipped pulp. Accordingly, the pesticide retention increased from 49.3% by weight to 80.0% by weight.

Example 6

In this example, the behavior of a known, with a cationic melamine formaldehyde colloid (Parez 607) charge-modified filter sheet (see US Pat. No. 4,007,113) with a
compared according to the invention with a cationic polyamido-polyaminepichlorohydrin resin (Hercules Polycup 1884) modified sheet.

A. Filter sheets were made from 70% by weight cellulose pulp system (CSF 130) and 30% by weight of a 50/50 mixture of diatomaceous earth and
Made perlite. They were formed in an identical manner by preparing a cationically disperse aqueous slurry, vacuum entangling it and imbibing the product
Oven dried except that optimized charge modifier levels (7% for Parez 6 07 and 2% for Hercules 1884) and drying conditions were used.

Using the test conditions described above, normalized streaming potential values were determined over time. Equilibrium flush curves for the respective
Filter media had been applied are compared in FIG. 1. It can be seen that the known (melamine-formaldehyde) media have an anomalous flushing curve which rises very rapidly to a peak and then slowly decreases over time. Accordingly, the sheets produced according to the invention show a steep

03003 9/0222

-3H-

The negative, normalized streaming potential is stabilized at a high equilibrium value, which is a high positive Indicates surface tension.

B. The same pilter media were then with contaminated liquid (0.109 μΐη Dow Diagnostics latex dispersion; 5.5 pH) provoked. The filtration performance and the normalized streaming potential were plotted against one another in FIGS. The well-known system (cationic melamine formaldehyde colloid) (Fig. 2) is with the invention, with polyamido-polyamine epichlorohydrin modified medium (Fig. 3) compared. The negatively charged latex particles were essentially initially quantitatively removed by electrokinetic trapping and absorption. The normalized streaming potential falls linearly decreases from a negative value through zero and then goes asymptotically towards a positive value. As the streaming potential approaches zero and passes through it, the turbidity of the Downflow from (breakthrough). This increase continues until the effluent opacity approaches the inlet opacity asymptotically, which is indicates that all of the latex is flowing through the filter media.

The filter sheets according to the invention (FIG. 3) retained their filtration behavior significantly longer than the known filter (Fig. 2).

Example 7

In this example, a further comparison between inventive Filter sheets and known filter sheets (melamine formaldehyde) carried out in the untreated state as well as in the state of an autoclave treatment and in the state of hot water rinsing. The latter treatments are used to sterilize the filter media used in biological fluids should be used.

030039/0222

A. Pilter sheets were produced and tested in the same way as in Example β, with the exception that, in addition to the untreated materials, further filter sheets were produced which under autoclave conditions (130 ⁰ C under a pressure of 6.8 kg over a period of 1 hour) or hot water rinsing conditions (1 hour with water at 82 ^° C. and a flow rate of 225 ccm / min). The results of the comparison of the streaming potentials are shown graphically in FIG.

It can be seen that the known (melamine-formaldehyde) modified filter media lost their positive charge under the conditions used for sterilization. In contrast, those with cationic polyamido-polyaminepichlorohydrin held modified filter sheets not only in terms of their effectiveness but they also showed improved behavior under the harsh conditions used.

B. The untreated and autoclaved filter media, prepared in Part A, underwent comparative membrane protection tests subject (inlet turbidity 50 NTü, 0.2 μm membrane, Flow rate 225 ml / min). The results obtained are shown in Table VII.

030039/0222 ORIGINAL BATHROOM

Table VII

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Sheet number. unt ehande11, P P. At first
(kg / cm ² Membrane protection test Time
(min) Pillow ^ AP
(kg / cm ² ) Membrane4AP
(kg / cm ² ) untreated, P P. 0.18 4P
) 55 0.08 0.35 55 2
untreated, I. I. 0.16 52 0.1 0.35 56 untreated, I. I. 0.11 45 0.29 0.35 57 treated in an autoclave, 0.14 52 0.35 0.12 58 treated in an autoclave, 0.15 16 0.035 0.35 59 treated in an autoclave, 0.15 17th 0.035 0.35 60 treated in an autoclave, 0.13 35 0.35 0.1 61 0.13 42 0.35 0.08 62

According to the prior art: 7% by weight of Parez 6 07 colloidal charge modifier

cationic melamine formaldehyde

According to the invention: 2% by weight Hercules 1884, polyamido-polyamine epichlorohydrin resin cationic charge modifier

It can be seen from the above values that the respective charge-modified Systems competitively responded untreated in these tests with "failure due to membrane clogging." in the case of the known system and by cushion clogging in the case of the system according to the invention However, after autoclaving, the membrane protection time in the known system was markedly impaired.

"Biological fluids" are to be understood herein as meaning liquid systems which are derived from living organisms or these are to be supplied and which are handled and treated in the customary manner under sterilized conditions so that sterilized media is required for filtration. Examples are isotonic solutions for I.M. or I.V. administration, solutions for administration per os as well as solutions for topical application, biological waste or other body fluids that are filterable Bodies may contain impurities, e.g. bacteria, viruses or pyrogens, which are expedient for examination or removal by immobilization or fixation on or entrapment in the filter medium, isolated or separated will.

Filter media according to the invention can be used alone or in combination used with other such media to pharmaceutica, such as antibiotics, saline solutions, dextrose solutions, Vaccines, blood plasma, serums, sterile water or eye washes, Beverages such as liqueurs, gin, vodka, beer, scotch, whiskey, sweet and dry wines, champagne or brandy, cosmetics, such as mouth rinsing liquids, perfumeries, shampoos, hair tonics, Face creams or shaving lotions, food products such as wine vinegar, vegetable oils, extracts, syrups, fruit juices, make-up water or cooking oils, chemicals such as antiseptics, Insecticides, photographic solutions, galvanic solutions, To treat cleaning compounds, solvents and lubricating oils and the like to remove submicron particles, bacterial To remove impurities and dissolve colloidal haze.

End of description. 0 3 0 0 3 9/0222

Claims (12)

Claims [1.) Sheet-shaped filter medium, characterized in that it is a a particulate material and a self-binding matrix contains of cellulose fibers, the surfaces at least des particulate material and / or the fibers have been modified with a cationic polyamido-polyamine epichlorohydrin resin, and wherein the matrix contains cellulosic fibers whipped to give a standard Canadian freedom of less than 600 ml. 2. Filter medium according to claim 1, characterized in that sufficient cationic resin is present to give at least the fibers and / or the particulate material a positive zeta potential to rent. 3. Filter medium according to claim 1 or 2, characterized in that that the resin is present in an amount of from about 1 to about 3 percent by weight is. 4. Filter medium according to one of claims 1 to 3, characterized in that that the fine, particulate material comprises at least 50% by weight of diatomaceous earth. . 5. Filter medium according to one of claims 1 to 4, characterized in that that the fine, particulate material is a mixture of diatomaceous earth and pearlite. 6. Filter medium according to one of claims 1 to 5, characterized in that that the fine, particulate material has an average particle dimension of less than about 10 μm. 030039/0222 7. Method of manufacturing a sheet-shaped filter medium for removal of submicron electronegative contaminants contaminated liquids, characterized in that there is a filter sheet made of a fine, particulate material and a Cellulose pulp system forms as a self-binding matrix, the Surfaces of at least the particulate material and / or the pulp with a cationic polyamido-polyamine epichlorohydrin resin and wherein the pulp system contains whipped pulp that gives the system a Canadian Standard Freedom of 100 up to 600 ml is awarded. 8. The method according to claim 7, characterized in that the sheet is made sterile or sterilized. 9. The method according to claim 8, characterized in that the sheet is treated in an autoclave. 10. The method according to claim 8, characterized in that the Rinses sheet with hot water. 11. Filter sheet to remove submicron contaminants Liquids characterized in that it comprises a sheet which from a cationically dispersible, aqueous slurry of cellulose pulp and fine particulate material has been vacuum felted, the filter sheet being made from a slurry containing whipped pulp such that a Canadian standard liberty of 100 to 600 ml is obtained, and wherein the surfaces of the particulate material and the cellulose pulp by treatment with a cationic polyamido-polyamine epichlorohydrin resin modified to show positive zeta potential. 12. Process for removing submicron contaminants from biological fluids, characterized in that the contaminated fluid is made sterile or sterilized Filter sheet made of a particulate material and a self-binding matrix, consisting of a cellulose powder 030039/0222 pesystem, wherein at least the particulate material and / or the pulp has been surface modified with a cationic polyamido-polyamine epichlorohydrin resin and wherein the cellulose pulp system contains pulp that is a matrix with a Canadian standard freeness of less than 600 ml
is obtained. 030039/0222