KR20160085832A - Coated microporous materials having filtration and adsorption properties and their use in fluid purification processes - Google Patents

Abstract

The present invention relates to a microfiltration membrane and an ultrafiltration membrane including a microporous material. The microporous material of the present invention comprises: (a) a polyolefin matrix present in an amount of at least 2% by weight; (b) a finely divided particulate substantially water-insoluble silica filler distributed throughout the matrix, (C) at least 20% by volume of a network of interconnecting pores communicating throughout the coated microporous material; and (c) at least 20% by volume of a network of interconnecting pores communicating throughout the coated microporous material, (d) at least one coating composition applied to at least one surface of the film to adjust the surface energy of the film.

Description

TECHNICAL FIELD [0001] The present invention relates to a coated microporous material having filtration and adsorption properties, and a use thereof in a fluid purification process. BACKGROUND OF THE INVENTION < RTI ID = 0.0 > [0001]

The present invention relates to coated microporous materials useful in filtration and adsorption membranes and their use in fluid purification processes.

Cross-reference to related application

This application claims the benefit of US Provisional Patent Application No. 61 / 555,500, filed November 4, 2011, which is a continuation-in-part of U.S. Patent Application No. 13 / 599,221 filed on August 30, 2012, November 12, 2013 Filed U.S. Patent Application Serial No. 14 / 077,741, filed on even date herewith, all of which are incorporated herein by reference.

Access to water and drinking water is a major concern globally, especially in developing countries. Investigations on inexpensive and effective filtration materials and processes are underway. Particularly preferred is a filtration medium which is capable of removing all of the visible particulate contaminants and molecular contaminants, including those that are capable of removing both hydrophilic and hydrophobic contaminants at low cost and high flow rates.

It is desirable to provide a novel membrane suitable for use with liquid or gaseous streams that serve to remove contaminants through both chemisorption and physisorption.

The present invention relates to a microfiltration membrane and an ultrafiltration membrane including a microporous material.

Microporous materials include the following:

(a) a polyolefin matrix present in an amount of at least 2% by weight,

(b) a finely divided particulate substantially water-insoluble silica filler distributed throughout the matrix, wherein the filler comprises about 10% to about 90% by weight of the coated microporous material substrate;

(c) at least 20% by volume of a network of interconnecting pores communicating throughout the coated microporous material, and

(d) at least one coating composition applied to at least one surface of the film to adjust the surface energy of the film.

All numbers expressing quantities of ingredients, reaction conditions, etc., used in the specification and claims, unless otherwise specified, or otherwise specified, are to be understood as being modified in all instances by the term "about. &Quot; Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and in an attempt to not limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently includes errors inherent in the standard deviation that are identified in their respective test measurements.

Also, any numerical range recited herein should be understood to include all subranges included therein. For example, a range of "1 to 10" includes all subranges between the cited minimum value of 1 and the cited maximum value of 10 (including their values), i.e., a minimum value exceeding 1 or 10, It is considered to include all subranges having a maximum value.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

It should be understood that the various embodiments and embodiments of the present invention presented herein are each non-limiting to the scope of the present invention.

The following terms used in the following description and claims have the meanings indicated below:

"Polymer" means homopolymers and copolymers, and polymers comprising oligomers. "Composite material" means a combination of two or more different materials.

 As used herein, the term "formed from" refers to an open claim language, e.g., "comprising." As such, it is contemplated that the composition "formed from the list of ingredients quoted is a composition comprising at least such recited ingredients during formation of the composition, and may further comprise other untested ingredients.

The term "polymeric inorganic material " as used herein means a polymeric material having a main chain repeating unit based on elements or elements other than carbon. For more information, see in particular James Market, et al., "Inorganic Polymers ", Prentice Hall Polymer Science and Engineering Series, (1992), page 5 ]. The term "polymeric organic materials " as used herein also means synthetic polymeric materials, semi-synthetic polymeric materials and natural polymeric materials having a main chain repeat unit based on carbon.

As used herein, the term "organic material " means a carbon-containing compound in which carbon is typically bonded to itself and hydrogen, including but not limited to, bicomponent compounds such as carbon oxides, carbides, carbon disulfide, and the like; Ternary compounds such as metallic cyanide, metallic carbonyl, phosgene, carbonyl sulfide and the like; And metallic carbonates, such as calcium carbonate and sodium carbonate, are excluded. This is specifically described in the literature, cf. Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed. 1993), pages 761-762, and M. M. Silberberg, Chemistry, Molecular Nature of Matter and Change (1996), p. 586].

The term "inorganic material " as used herein means any material that is not an organic material.

A "thermoplastic" material as used herein is a material that softens when exposed to heat and returns to its original state when cooled to room temperature. A "thermoset" material, as used herein, is a material that is irreversibly solidified or "sets" upon heating.

As used herein, "microporous material" or "microporous sheet material" refers to a material that is free of coatings, free of printing ink, free of impregnants, and based on pre-bonded conditions Means a material having a network of interconnected pores, wherein the pores have a volume average diameter in the range of 0.001 to 0.5 micrometers (占 퐉) and constitute at least 5% by volume of the material as discussed herein.

"Plastomer" means a polymer that exhibits both plastic and elastomeric properties.

As mentioned above, the present invention relates to a microfiltration membrane and an ultrafiltration membrane comprising a microporous material. The microporous material used in the membrane of the present invention comprises a polyolefin matrix (a). The polyolefin matrix is present in the microporous material in an amount of at least 2% by weight. The polyolefin is a polymer derived from at least one ethylenically unsaturated monomer. In certain embodiments of the invention, the matrix comprises a plastomer. For example, the matrix may include plastomers derived from butene, hexene, and / or octene. Suitable plastomers are commercially available from ExxonMobil Chemical under the trade name "EXACT ".

In certain embodiments of the present invention, the matrix comprises other polymers derived from at least one ethylenically unsaturated monomer that can be used in place of a plastomer or in combination with a plastomer. Examples thereof include polymers derived from ethylene, propylene, and / or butene, such as polyethylene, polypropylene, and polybutene. High density and / or ultra high molecular weight polyolefins such as high density polyethylene are also suitable.

In certain embodiments of the present invention, the polyolefin matrix comprises a copolymer of ethylene and butene.

Non-limiting examples of ultra high molecular weight (UHMW) polyolefins may include UHMW polyethylene or polypropylene which is essentially linear. Considering that UHMW polyolefins are not thermoset polymers with an infinite molecular weight, they are technically classified as thermoplastic.

The ultra high molecular weight polypropylene may comprise an essentially linear ultra high molecular weight isotactic polypropylene. Usually, the isotacticity of such polymers is at least 95%, for example at least 98%.

Although there is no particular limitation on the upper limit of the intrinsic viscosity of UHMW polyethylene, in one non-limiting embodiment, the intrinsic viscosity is in the range of 18 to 39 deciliter per gram (dl / g), for example in the range of 18 to 32 dl / g Lt; / RTI > There is no particular limitation on the upper limit of the intrinsic viscosity of the UHMW polypropylene, but in one non-limiting example, the intrinsic viscosity may range from 6 to 18 dl / g, for example from 7 to 16 dl / g.

For purposes of the present invention, intrinsic viscosity is measured by extrapolating the reduced viscosity or intrinsic viscosity of several dilute solutions of UHMW polyolefin to zero concentration, wherein the solvent is 0.2 wt% 3,5-di-t-butyl -4-hydroxyhydrocinnamic acid, neopentanetetrayl ester [CAS Reg. No. 6683-19-8], is added to the distilled decahydronaphthalene. The reduced viscosity or intrinsic viscosity of the UHMW polyolefin was measured using a Ubbelohde No. 1 viscometer according to the general procedure of ASTM D 4020-81 except that several dilution solutions with different concentrations were used, Lt; RTI ID = 0.0 > 135 C. < / RTI >

The nominal molecular weight of UHMW polyethylene is experimentally related to the intrinsic viscosity of the polymer according to the following equation:

In the above equation,

M is the nominal molecular weight of UHMW polyethylene,

는 데시리터/그램(dl/g)으로 나타내는 UHMW 폴리에틸렌의 고유 점도이다.

Is the intrinsic viscosity of UHMW polyethylene, expressed in deciliter / gram (dl / g).

Similarly, the nominal molecular weight of UHMW polypropylene is experimentally related to the intrinsic viscosity of the polymer according to the following equation:

M is the nominal molecular weight of UHMW polypropylene,

는 dl/g으로 나타내는 UHMW 폴리프로필렌의 고유 점도이다.

Is the intrinsic viscosity of the UHMW polypropylene expressed in dl / g.

Mixtures of substantially linear ultra-high molecular weight polyethylene and low molecular weight polyethylene may be used. In certain embodiments, the UHMW polyethylene has an intrinsic viscosity of at least 10 dl / g and the low molecular weight polyethylene has an ASTM of less than 50 g / 10 min, such as less than 25 g / 10 min, such as less than 15 g / D 1238-86 condition E melt index and a melt index of at least 0.1 g / 10 min, such as less than 0.5 g / 10 min, such as less than 1.0 g / 10 min ASTM D 1238-86 Condition F melt index. The amount (as weight percent) of UHMW polyethylene used in this embodiment is described in column 1, line 52 to column 2, line 18 of U.S. Patent No. 5,196,262, the disclosure of which is incorporated herein by reference. More particularly, the weight percent of UHMW polyethylene used is described with reference to FIG. 6 of U.S. Patent 5,196,262, that is, the polygon ABCDEF, GHCI, or JHCK of FIG. 6, which is incorporated herein by reference.

The nominal molecular weight of low molecular weight polyethylene (LMWPE) is lower than the nominal molecular weight of UHMW polyethylene. LMWPE is a thermoplastic material and various types are known. One classification method is the density according to ASTM D 1248-84 (reinstated 1989), expressed in grams per cubic centimeter (g / cm 3) and rounded to the nearest one thousandth. A non-limiting example of the density of LMWPE is shown in Table A below.

Table A

Some or all of the polyethylenes listed in Table 1 above can be used as LMWPE in a matrix of microporous materials. HDPE can be used because it can be more linear than MDPE or LDPE. Processes for making various LMWPEs are well known and well documented. These processes include a high pressure process, a process by Phillips Petroleum Company, a process by Standard Oil Company of Indiana, and a Ziegler process. The melt index according to ASTM D 1238-86 Condition E (i.e., 190 ° C and 2.16 kg load) of LMWPE is less than about 50 g / 10 min. Usually, the condition E melt index is less than about 25 g / 10 min. The condition E melt index can be less than about 15 g / 10 min. The melt index of LMWPE according to ASTM D 1238-86 Condition F (i.e., 190 ° C and 21.6 kg load) is at least 0.1 g / 10 min. In many cases, the conditional F melt index is at least 0.5 g / 10 min, for example at least 1.0 g / 10 min.

UHMWPE and LMWPE may together constitute at least 65%, for example at least 85%, by weight of the polyolefin polymer of the microporous material. In addition, UHMWPE and LMWPE may together constitute substantially 100% by weight of the polyolefin polymer of the microporous material.

In certain embodiments of the present invention, the microporous material may comprise a polyolefin comprising ultra-high molecular weight polyethylene, ultra-high molecular weight polypropylene, high density polyethylene, high density polypropylene, or mixtures thereof.

In some cases, other thermoplastic organic polymers may also be present in the matrix of microporous material, but their presence does not substantially adversely affect the properties of the microporous material substrate in a negative manner. The amount of other thermoplastic polymer that may be present depends on the nature of such a polymer. Generally, the molecular structure will contain a larger amount of branch, a larger long chain side chain, or a larger amount when it contains fewer branches, some long chain side chains, and some fewer chain side branches, Of other thermoplastic organic polymers may be used. Non-limiting examples of thermoplastic organic polymers that may optionally be present in the matrix of microporous material include low density polyethylene, high density polyethylene, poly (tetrafluoroethylene), polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and acrylic acid , And copolymers of ethylene and methacrylic acid. In some cases, all or a portion of the carboxyl groups of the carboxyl-containing copolymer may be neutralized with sodium, zinc, and the like. Generally, the microporous material comprises at least 70 wt% UHMW polyolefin, based on the weight of the matrix. In a non-limiting embodiment, the other thermoplastic organic polymer described above is substantially absent from the matrix of microporous material.

The microporous material used in the membrane of the present invention further comprises a finely divided particulate substantially water-insoluble silica filler (b) distributed throughout the matrix.

The particulate filler typically comprises precipitated silica particles. The distinction of precipitated silica from silica gel is important in that these different materials have different properties. Reference in this regard is provided in the entire disclosure of which is incorporated herein by reference in its entirety. K. R. K. Iler, "The Chemistry of Silica ", John Wiley & Sons, New York (1979). Library of Congress Catalog No. QD 181.S6144]. In particular, it should be noted that pages 15-29, 172-176, 218-233, 364-365, 462-465, 554-564, and 578-579. Silica gels are generally produced commercially at low pH by acidifying an aqueous solution of a soluble metal silicate, typically sodium silicate, with an acid. Carbon dioxide is sometimes used, but the acid used is generally a strong inorganic acid such as sulfuric acid or hydrochloric acid. Since there is essentially no difference in density between the gel phase and the surrounding liquid phase while the viscosity remains low, the gel phase does not settle, i.e., it does not settle. In addition, the silica gel can be described as a non-sedimented, rigid three dimensional network of adjacent particles of colloidal amorphous silica. The subdivision ranges from a large solid mass to a very fine particle, and the degree of hydration is in the range from soft anhydrous silica to soft gelatinous mass containing approximately 100 parts water by weight of silica.

The precipitated silica is generally prepared by combining an aqueous solution of a soluble metal silicate, typically an alkali metal silicate such as sodium silicate, and an acid, such that the colloidal particles grow in a weakly alkaline solution and aggregate by the alkali metal ions of the resulting alkali metal salt It is produced commercially. A variety of acids including inorganic acids can be used, but the preferred acid is carbon dioxide. In the absence of coagulant, silica is not precipitated from the solution at a particular pH. The coagulant used to effect the precipitation may be a soluble alkali metal salt formed during the formation of the colloidal silica particles, or may be an added electrolyte such as a soluble inorganic or organic salt, or a combination thereof.

Also, precipitated silica can be described as precipitated aggregates of small particles of colloidal amorphous silica that do not have a particular spot present as a macroscopic gel during manufacture. The size and degree of hydration of the agglomerates can vary widely.

The precipitated silica powder is typically different from the silica gel pulverized to have a more open structure, i.e. a higher specific pore volume. However, the specific surface area of the precipitated silica measured by the Brunauer, Emmet, Teller (BET) method using nitrogen as the adsorbent is usually lower than the specific surface area of the silica gel.

Although many different precipitated silicas can be used in the present invention, preferred precipitated silicas are those obtained by precipitation from an aqueous solution of sodium silicate using an appropriate acid such as sulfuric acid, hydrochloric acid, or carbon dioxide. Precipitated silicas are known per se, and their preparation processes are described in more detail in U.S. Patent Nos. 2,940,830 and 2,040,142, the entire disclosures of which are incorporated herein by reference, including in particular the processes for making precipitated silica and the properties of the products Is disclosed in detail in the publication 35 45 615.

The precipitated silica used in the present invention can be produced by a process comprising the following sequential steps:

(a) preparing an initial stock solution of an aqueous alkali metal silicate having the desired degree of alkalinity, and then adding (or producing in a reactor) a reactor equipped with means for heating the contents of the reactor,

(b) heating the initial mother liquor in the reactor to the desired reactor temperature,

(c) simultaneously adding the acidifying agent and the further alkali metal silicate solution to the reactor with stirring while maintaining the alkalinity value and temperature of the contents of the reactor at the desired values,

(d) stopping the addition of the alkali metal silicate to the reactor and then adding an additional acidifying agent to adjust the pH of the resulting suspension of precipitated silica to the desired acid,

(e) separating the precipitated silica in the reactor from the reaction mixture and washing to remove the byproduct salt, and

(f) drying to form precipitated silica.

The washed silica solids are then dried using conventional drying techniques. Non-limiting examples of such techniques include oven drying, vacuum oven drying, rotary drying, spray drying or spin flash drying. Non-limiting examples of spray dryers include rotary sprayers and nozzle spray dryers. Spray drying can be carried out using certain suitable types of atomisers, particularly turbines, nozzles, liquid-pressure or twin-fluid atomizers.

The washed silica solids may not be suitable for spray drying. For example, the washed silica solids may be too thick to spray dry. In one embodiment of the above-described process, the washed silica solids, e. G., The washed filter cake, are mixed with water to form a liquid suspension and, in some cases, dilute acid or dilute alkali, , The pH of the suspension is adjusted to 6 to 7, for example, 6.5, and then supplied to the inlet nozzle of the spray dryer.

The temperature at which the silica is dried may be very wide but will be below the fusion temperature of the silica. Typically, the drying temperature will be in the range of 50 ° C to less than 700 ° C, for example 100 ° C, for example 200 ° C to 500 ° C. In one embodiment of the above-described process, the silica solids are dried in a spray dryer having an inlet temperature of approximately 400 캜 and an outlet temperature of approximately 105 캜. The free water content of the dried silica can vary, but generally ranges from about 1 to 10% by weight, for example from 4 to 7% by weight. The term ratios as used herein means water which can be removed from the silica by heating it at 100 占 폚 to 200 占 폚, for example, at 105 占 폚 for 24 hours.

In one embodiment of the process described herein, the dried silica is delivered directly to the granulator, where it is pressed and granulated to yield a granulation product. The dried silica may also be treated with a conventional size reduction technique as exemplified by, for example, grinding and milling. Also, a fluid energy milling method using air or superheated steam as the working fluid may be used. The precipitated silica obtained is generally in the form of a powder.

In most cases, the precipitated silica is spin-dried or spray-dried. The spin dried silica particles were observed to exhibit greater structural integrity than the spray dried silica particles. They are less likely to be crushed into smaller particles during extrusion and other subsequent processing during the production of microporous material than spray dried particles. The particle size distribution of spin-dried particles does not change much as does the particle size distribution of spray-dried particles during processing. The spray dried silica particles are more crumbly than the spin-dried silica particles and usually provide smaller particles during operation. Spray dried silica having a specific particle size can be used so that the final particle size distribution in the membrane does not adversely affect the water flux. In certain embodiments, the silica is reinforced (i. E., It has structural integrity such that porosity is preserved even after extrusion). Even more preferred are precipitated silicas wherein the initial number of silica particles and the initial silica particle size distribution are hardly changed by the stress applied during the fabrication of the membrane. Silica reinforced so that a broad particle size distribution is present in the final film is most preferred. Different types of dried silica and blends of silica of different sizes may be used to provide membrane-specific properties. For example, a blend of silica with a bimodal distribution of particle sizes may be particularly suitable for certain separation processes. It is expected that an external force applied to a particular type of silica will affect the particle size distribution and adjust it to provide unique properties to the final membrane.

The surface of the particles may be modified in any manner well known in the art, including methods of chemically or physically changing the surface properties of the particles using techniques known in the art, It is not limited. For example, silica can be a surface treated with an anti-fouling moiety such as polyethylene glycol, carboxybetaine, sulfobetaine and polymers thereof, mixed atom molecules and oligomers and polymers thereof, and mixtures thereof. have. In another embodiment, one silica may be treated with positively charged residues and the other silica may be a blend of silica treated with negatively charged residues. The silica may also be a surface modified with a functional group capable of targeted removal of certain contaminants in the fluid stream to be purified using the microfiltration membrane of the present invention. In addition, untreated particles may be used. Silica particles coated with a hydrophilic coating can reduce contamination and eliminate the pre-wet treatment process. Silica particles coated with a hydrophobic coating can also reduce contamination and aid in degassing and evacuating the system.

The precipitated silica typically has an average ultimate particle size of 1 to 100 nanometers.

The surface area of the silica particles can affect performance both outside and inside due to pores. A high surface area filler is a material having a very small particle size, a material having a high porosity, or a material exhibiting both of these properties. In general, the surface area of the filler itself was measured by the Brunauer, Emmet, Teller (BET) method according to ASTM C 819-77 using nitrogen as the adsorbent, but the system and sample were degassed ) To about 700 square meters per square meter (m < 2 > / g) per gram. Generally, the BET surface area is in the range of about 190 to 350 m < 2 > / g, more generally, the silica exhibits a BET surface area of 351 to 700 m &

The BET / CTAB index is the ratio of the total settled silica surface area, including the surface area contained within the pores, accessible only to smaller molecules such as nitrogen (BET) for the outer surface area (CTAB). This ratio is typically referred to as a measure of microporosity. A high microporosity value, i.e. a high BET / CTAB index, is a high proportion of the inner surface (small nitrogen molecules accessible but larger particles inaccessible) (BET surface area) to the outer surface (CTAB).

It has been suggested that the structure formed in the precipitated silica during manufacturing, i.e., pores, can affect performance. The two measurements of this structure are the relative breadth (y) of the BET / CTAB surface area ratio of the precipitated silica mentioned above, and the pore size distribution of the precipitated silica. The relative width (y) of the pore size distribution is an indicator of how widely the pore size is distributed within the precipitated silica particles. The lower the y value, the narrower the pore size distribution of the pores in the precipitated silica particles.

The silica CTAB value can be measured using a CTAB solution and the method described below. The analysis was performed using a Metrohm 751 Titrino automatic titrator with a Metrohm Interchangeable "Snap-In" 50 milliliter burette and a Brinkman probe with a 550 nm filter This is done using a Brinkmann Probe Colorimeter Model PC 910. Further, Mettler Toledo (Mettler Toledo) HB43 or equivalents will be used to measure the 105 ℃ water loss of silica, Fisher Scientific Sentry pick ^TM (Fisher Scientific Centrific ^TM) centrifuge model 225 is to separate the silica and the residual CTAB solution Can be used. Excess CTAB can be measured by automated titration with a solution of Aerosol OT ^® (Aerosol OT ^®) until it reaches the maximum turbidity that can be detected by a probe colorimeter. The maximum turbidity point is considered to correspond to a millivolt measurement of 150. Knowing the amount of CTAB adsorbed to a given weight of silica and the space occupied by CTAB molecules, the external specific surface area of the silica is calculated and reported as square meters per gram (m 2 / g) based on the dry weight.

The solution required for testing and manufacturing includes buffered solution of pH 9.6, cetyl [hexadecyl] trimethylammonium bromide (CTAB), dioctyl sodium sulfosuccinate (aerosol OT) and 1N sodium hydroxide. The buffer solution at pH 9.6 was added to a 1-L volumetric flask containing 500 ml of deionized water and 3.708 g of potassium chloride solids (Fisher Scientific, Inc., commercial grade, crystalline) By dissolving orthoboric acid (99%; Fisher Scientific, Inc., industrial grade, crystalline). 36.85 ml of 1N sodium hydroxide solution was added using a burette. Mix the solution and dilute to the desired volume.

On the weighing dish, 11.0 g 0.005 g of powdered CTAB (cetyltrimethylammonium bromide, also known as hexadecyltrimethylammonium bromide, Fisher Scientific, Inc., industrial) was added to the CTAB solution . The CTAB powder was transferred to a 2-L beaker and the weighing dish was rinsed with deionized water. Approximately 700 ml of pH 9.6 buffer and 1000 ml of distilled or deionized water are added to the 2-L beaker and then stirred with a magnetic stir bar. The beaker can be covered and then stirred at room temperature until the CTAB powder is completely dissolved. The solution is transferred to a 2-L volume flask and the beaker and stir bar are rinsed with deionized water. The bubble may be lost and the solution is diluted to the desired volume with deionized water. A large stir bar may be added and the solution is mixed on a magnetic stirrer for approximately 10 hours. The CTAB solution can be used from 24 hours to only 15 days. Aerosol ^® OT (dioctyl sodium sulfosuccinate, Fisher Scientific,, Inc., 100% solids) solution can be prepared using 3.46g ± 0.005g placed on a weighing dish. Aerosol OT, placed on a weighing dish, is rinsed in a 2-L beaker containing about 1500 ml deionized water and a large stir bar. The aerosol OT solution is dissolved and rinsed in a 2-L volumetric flask. The solution is diluted in a measuring flask to the 2-L volume mark. Then aged for a minimum of 12 days Aerosol OT ^® solution before use. The shelf life of the aerosol OT solution is 2 months from the date of manufacture.

Before preparing the surface area sample, the pH of the CTAB solution should be checked and, if necessary, adjusted to a pH of 9.6 ± 0.1 using 1N sodium hydroxide solution. For the test operation, a blank sample must be prepared and analyzed. 5 ml of CTAB solution was pipetted and 55 ml of deionized water was added to the 150 ml beaker and analyzed on a Methlot 751 Titriino automatic titrator. The automatic titrator is programmed with the following parameters to measure blank and sample: Measurement point density = 2, Signal drift = 20, Equilibration time = 20 seconds, Starting volume = 0 ml, Stop volume = 35 ml, And Fixed endpoint = 150 mV. The buret tip and colorimetric probe are positioned directly beneath the surface of the solution positioned so that the tip and photo-probe path length are fully immersed. Both the tip and the photo-probe should be essentially equidistant from the bottom of the beaker and not contact each other. Despite the minimum agitation (set to 1 on the Metrom 728 agitator), the colorimeter is set to 100% T before all blank and sample measurements and titration with Aerosol OT ^® solution are initiated. The end point can be recorded as the volume (ml) of the titrant at 150 mV.

To prepare the test sample, approximately 0.30 g of silica powder was weighed into a 50-ml vessel containing a stir bar. The granulated silica sample was reflowed (before grinding and weighing) to obtain a representative sub-sample. The granulated material was polished using a coffee mill style polisher. Then 30 ml of pH adjusted CTAB solution was pipetted into a sample vessel containing 0.30 g of silica powder. The silica and CTAB solution were then mixed on a stirrer for 35 minutes. When the mixing was complete, the silica and CTAB solution were centrifuged for 20 minutes to separate the silica and excess CTAB solution. When the centrifugation was complete, the CTAB solution was pipetted into a clean container from which the separated solids, referred to as "centrifugate ", were removed. For sample analysis, 50 ml of deionized water was placed in a 150-ml beaker containing a stir bar. Then, 10 ml of the sample centrifuge was pipetted into the same beaker for analysis. Samples were analyzed using the same techniques and programmed procedures as those used for blank solutions.

To determine the moisture content, approximately 0.2 g of silica was weighed on a Mettler Toledo HB43 while measuring the CTAB value. The moisture analyzer was programmed at 105 ° C using the shut-off 5 drying criteria. Water loss was recorded close to + 0.1%.

The external surface area is calculated using the following equation:

CTAB surface area (dry basis) [m 2 / g] =

In this formula,

V ₀ = volume of Aerosol OT ^® used in the blank titration (ml).

V = volume of Aerosol OT ^® used in the sample titration (ml).

W = sample weight (g).

Vol =% water loss (Vol indicates "volatile").

Typically, the CTAB surface area of the silica particles used in the present invention is in the range of 120 to 500 m < 2 > / g. Generally, the silica exhibits a CTAB surface area of 170 to 280 m < 2 > / g. More generally, the silica exhibits a CTAB surface area of 281 to 500 m < 2 > / g.

In certain embodiments of the present invention, the BET value of the precipitated silica will be such that the ratio of the BET surface area (m 2 / g) to the CTAB surface area (m 2 / g) is 1.0 or greater. Generally, the BET to CTAB ratio is 1.0 to 1.5. More generally, the BET to CTAB ratio is 1.5 to 2.0.

The BET surface area values reported in the examples of this application were determined according to the Brunauer-Emmett-Teller (BET) method according to ASTM D1993-03. The BET surface area can be measured by fitting five relative-pressure points from nitrogen absorption isotherm measurements made using a Micromeritics TriStar 3000 ^TM instrument. Flow Prep-060 ^TM station (Flow Prep-060 ^TM station provides heat and continuous gas flow for producing analytical samples. Prior to nitrogen uptake, the silica sample is heated to 160 < 0 > C for at least 1 hour in flowing nitrogen (grade P5) and dried.

The filler particles may constitute from 10 to 90% by weight of the microporous material. For example, such filler particles may comprise from 25 to 90 weight percent of the microporous material, such as from 30 to 90 weight percent of the microporous material, or from 40 to 90 weight percent of the microporous material, or from 50 to 90 weight percent of the microporous material. By weight, or from 60 to 90% by weight of the microporous material. The filler is typically present in the microporous material of the present invention in an amount of from about 50% to about 85% by weight of the microporous material. Generally, the weight ratio of silica: polyolefin in the microporous material is from 0.5: 1 to 10: 1, such as from 1.7: 1 to 3.5: 1. Alternatively, the weight ratio of filler to polyolefin in the microporous material may exceed 4: 1.

The microporous material used in the membrane of the present invention further comprises a network (c) of interconnecting pores communicating throughout the microporous material.

Based on the absence of the impregnant, such pores may account for at least 15 vol%, such as at least 20 to 95 vol%, or at least 25 to 95 vol%, or 35 to 70 vol%, of the microporous material. Generally, the pores account for at least 35%, or at least 45% by volume, of the microporous material. This high porosity provides a high surface area throughout the microporous material, which in effect actually removes contaminants from the fluid stream through the membrane and promotes a higher flow rate of the fluid stream.

As used herein and in the claims, the porosity (also referred to as pore volume) of the microporous material, expressed as volume%, is measured according to the following equation:

Porosity = 100 [1-d ₁ / d ₂ ]

In this formula,

d ₁ is the density of the sample measured from the sample weight and the sample volume, as determined from the measurement of the sample dimensions, and d ₂ is the density of the solid portion of the sample as measured from the sample weight and the volume of the solid portion of the sample. The volume of the solid portion of the same sample is measured according to the attached operating manual using a Quantachrome stereopycnometer (manufactured by Quantachrome Corp.).

The volume average diameter of the microporous material was measured using an Autopore III porosimeter (Micromeretics, Inc.) under the mercury porosimetry method according to the attached operating manual porosimetry). The volume average pore radius for a single scan is automatically measured by a porosimeter. When the porosimeter is activated, the scan is performed in the high pressure range (138 kPa absolute to 227 Mega Pascal absolute pressure). When less than about 2% of the total intruded volume occurs at the low end of the high pressure range (138 to 250 kilopascals absolute pressure), the volume average pore diameter is the volume average porosity measured by the porosimeter It is considered to be twice the radius. Otherwise, a scan is made in the low pressure range (7 to 165 kilopascals absolute pressure) and the volume average pore diameter is calculated according to the following equation:

d = 2 [v ₁ r ₁ / w ₁ + v ₂ r ₂ / w ₂ ] / [v ₁ / w ₁ + v ₂ / w ₂ ]

In this formula,

d is the volume average pore diameter, v ₁ is the total volume of mercury penetrated in the high pressure range, v ₂ is the total volume of mercury penetrated in the low pressure range, r ₁ is the volume average pore radius measured from the high pressure scan, r ₂ is the volume average pore radius measured from the low pressure scan, w ₁ is the weight of the high pressure scanned sample, and w ₂ is the weight of the low pressure scanned sample. In the case of an ultrafiltration membrane, the volume average diameter (average pore size) of the pores is typically less than 0.1 micrometers (microns) and may range from 0.001 to 0.70 micrometers, for example, from 0.30 to 0.70 micrometers. For microfiltration membranes, the average pore size typically exceeds 0.1 micrometers (microns).

In the process of measuring the volume average pore diameter of the above procedure, the maximum pore radius detected is often mentioned. Which, when executed, is obtained from a low pressure range scan; Otherwise, it is obtained from the high-pressure range scan. The maximum pore diameter is twice the maximum pore radius. Some production or processing steps, such as coating, printing, impregnation, and / or bonding processes, can result in the filling of at least a portion of the pores of the microporous material, and some of these processes are irreversible The parameters relating to porosity, volume average diameter of the pores, and maximum pore diameter are measured for the microporous material prior to applying one or more of these production or processing steps.

To prepare the microporous material of the present invention, the filler, polymer powder (polyolefin polymer), processing plasticizer, and trace amounts of lubricant and antioxidant are mixed until a substantially homogeneous mixture is obtained. The weight ratio of filler to polymer powder used to form the mixture is essentially the same as the weight ratio of the microporous material substrate to be produced. The mixture is introduced into a heated barrel of a screw extruder with an additional processing plasticizer. To form the desired final shape, a die, such as a sheet die, is attached to the extruder.

In an exemplary manufacturing process, when the material is formed into a sheet or film, the continuous sheet or film formed by the die is transferred to a cooperating pair of heated calender rolls to form a continuous sheet less thicker than the continuous sheet discharged from the die . The final thickness may depend on the intended end use application. The microporous material may be in the range of 0.7 to 18 mils (17.8 to 457.2 microns), such as 0.7 to 15 mils (17.8 to 381 microns), or 1 to 10 mils (25.4 to 254 microns), or 5 to 10 mils 127 to 254 microns), and may exhibit a bubble point of 10 to 80 psi based on ethanol.

Optionally, the sheet subsequently discharged from the calender roll may be stretched in at least one stretching direction above the elastic limit, depending on whether the film to be formed is for microfiltration or ultrafiltration. Alternatively, the elongation may occur during or immediately after discharge from the sheet die, or during calendering, or multiple times, but typically before extraction. The oriented microporous material substrate can be prepared by stretching the intermediate product in at least one stretching direction above the elastic limit. Generally, the elongation is at least about 1.5. In many cases, the elongation is at least about 1.7. Preferably, the elongation is at least about 2. Often, the elongation is in the range of about 1.5 to about 15. Usually, the elongation is in the range of about 1.7 to about 10. Generally, the elongation is in the range of from about 2 to about 6. However, care must be taken to ensure that the pore size does not become too large for ultrafiltration.

The temperature at which stretching is performed can vary greatly. Stretching can be performed at approximately ambient room temperature, but elevated temperatures are generally used. The intermediate product can be heated before, during, and / or after stretching using a particular technique among a wide variety of techniques. Examples of such techniques include radiant heating provided by an electrically heated or gas fired infrared heater, convection heating provided by hot air, and conductive heating provided by contact with a heating roll . The temperature measured for temperature control purposes may vary depending on the equipment used and the personal preference. For example, the temperature-measuring apparatus can measure the temperature of the surface of the infrared heater, the temperature of the inside of the infrared heater, the temperature of the air at the point between the infrared heater and the intermediate product, The temperature of the surface of the roll used in the stretching process, the temperature of the heat transfer fluid entering or leaving the roll, or the film surface temperature. In general, the temperatures or temperatures are such that the intermediate product can, if appropriate, change in film thickness of the stretched microporous material to within an acceptable limit and the amount of stretched microporous material outside of this limit range is acceptable So as to be as low as possible. The temperatures used for the control purposes may be close to or close to the temperature of the intermediate product itself because of the nature of the device in which they are used, the location of the temperature-measuring device and the similarity of the substance or object to be measured It will be obvious that you may not.

Given the position and line speed of the heating device typically used during stretching, the gradient of varying temperature may or may not be present over the thickness of the intermediate product. Also, due to this line speed, it is almost impossible to measure such a temperature gradient. The presence of a varying temperature gradient makes it unreasonable to refer to a single film temperature when they occur. Thus, the film surface temperature that can be measured is best used to characterize the thermal state of the intermediate product.

They are generally approximately equal across the width of the intermediate product during stretching, although they may be intentionally varied to compensate for intermediate products having a wedge-shaped cross-section across the sheet, for example, so to speak. The film surface temperature may be approximately the same along the length of the sheet, or they may differ during stretching.

The film surface temperature at which stretching is attained may vary widely, but is generally the temperature at which the intermediate product is drawn substantially uniformly, as described above. In most cases, the film surface temperature during stretching ranges from about 20 캜 to about 220 캜. Usually, such temperatures range from about 50 ° C to about 200 ° C. And preferably from about 75 캜 to about 180 캜.

Stretching can be accomplished in a single step or, in some cases, in multiple steps. For example, if the intermediate product is unidirectionally stretched (uniaxially stretched), the stretching can be accomplished by a single stretching step or a sequential stretching step until the desired final stretch rate is achieved. Similarly, when the intermediate product is stretched in two directions (biaxially stretched), the stretching can be performed by a single biaxial stretching step or a sequential biaxial stretching step until the desired final stretching ratio is achieved. Biaxial stretching may also be performed by one or more uniaxial stretching steps in a sequential one direction and by one or more uniaxial stretching steps in another direction. The biaxial stretching step in which the intermediate product is simultaneously stretched in two directions, and the uniaxial stretching step can be sequentially performed in an arbitrary order. Stretching in two or more directions is considered. It can be seen that there are quite a number of variations of these steps. In some cases, other steps such as cooling, heating, firing, annealing, reeling, unreeling, etc. may optionally be included in the overall process.

Various types of stretching devices are well known and can be used to effect stretching of the intermediate product. Uniaxial stretching is generally performed by stretching between two rollers, in which the second or downstream rollers rotate at a greater peripheral speed than the first or upstream rollers. Uniaxial stretching may also be performed on a standard tentering machine. Biaxial stretching can be performed by stretching simultaneously in two different directions on the long stretcher. However, more typically, biaxial stretching may be effected by first uniaxially stretching between two different rotating rollers as described above, followed by uniaxially stretching in different directions using a long stretcher, or by biaxial stretching . The most common type of biaxial stretching is when two stretching directions are nearly perpendicular to each other. In most cases in which the continuous sheet is stretched, one stretching direction is at least substantially parallel to the long axis (machine direction) of the sheet, and the other stretching direction is at least almost perpendicular to the machine direction and exists in the plane (lateral direction) of the sheet.

Stretching the sheet prior to the extraction of the processing plasticizer may result in a larger pore size than in conventionally treated microporous materials, so that a microporous material particularly suitable for use in the microfiltration membrane of the present invention can be prepared. It is also believed that stretching the sheet prior to extraction of the processing plasticizer minimizes the heat shrinkage after processing.

The product passes through a first extraction zone in which the processing plasticizer is substantially removed by extraction with a good solvent for the processing plasticizer, a poor solvent for the organic polymer, and an organic liquid that is more volatile than the processing plasticizer. Generally, though not essential, the processing plasticizer and the organic extraction liquid are all substantially incompatible with water. The product then passes through a second extraction zone in which the residual organic extraction liquid is substantially removed by steam and / or water. The product is then passed through a ventilation dryer for substantially removing the remaining water and remaining residual organic extraction liquid. In the dryer, the microporous material may pass through a take-up roll when it is in sheet form.

The processing plasticizer has a slight solvation effect on the thermoplastic organic polymer at 60 占 폚, only a moderate solvation effect at an elevation temperature of about 100 占 폚, and a considerable solvation effect at an elevation temperature of about 200 占 폚. It is liquid at room temperature and is generally a processing oil such as paraffinic oil, naphthenic oil, or aromatic oil. Suitable processing oils include those that meet the requirements of ASTM D 2226-82, Types 103 and 104. Oils with a pour point of less than 22 占 폚, or less than 10 占 폚, according to ASTM D 97-66 (reaffirmed in 1978), are most commonly used. Examples of suitable oils include solvent refined and hydrotreated oils derived from naphthenic crude oil, Shellflex® 412 and Shellflex® 371 oil (Shell Oil Co.) . Other materials including phthalate ester plasticizers such as dibutyl phthalate, bis (2-ethylhexyl) phthalate, diisodecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, and ditridecyl phthalate satisfactorily function as processing plasticizers .

There are many organic extraction liquids that can be used. Examples of suitable organic extraction liquids include 1,1,2-trichlorethylene, perchlorethylene, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, methylene chloride , Chloroform, isopropyl alcohol, diethyl ether and acetone.

In the above-described process for producing a microporous material substrate, extrusion and calendering are promoted when the filler has a high processing plasticizer. The capacity of the filler particles to absorb and retain the processing plasticizer is a function of the surface area of the filler. Thus, the filler typically has a high surface area as discussed above. Considering that it is desirable to essentially retain the filler in the microporous material substrate, the filler may be substantially insoluble in the processing plasticizer when the microporous material substrate is produced by the process and is substantially Should be insoluble.

The residual processing plasticizer content is generally less than 15% by weight of the resulting microporous material, which can be further reduced to the same level as less than 5% by weight by further extraction using the same or a different organic extraction liquid.

The resulting microporous material may be further treated according to the intended use. In the present invention, a hydrophilic coating may be applied to the surface of the microporous material to adjust the surface energy of the material. Without wishing to be bound by theory, it is believed that the components of this coating interact with the silica particles in the filler of the microporous material and modulate the surface energy that affects the wettability. The coating may be applied before, during, or after the stretching step described above, but may generally be performed simultaneously with the stretching step to maximize the coating range for additional surface area produced during the stretching process.

Hydrophilic coatings include poly (2-ethyl-2-oxazoline), poly (2-methyl-2-oxazoline) Oxazoline; Triblock copolymers based on poly (ethylene glycol) -poly (propylene glycol) -poly (ethylene glycol); Polyethylene imine; Polyamide; Oxidized polyethylene or derivatives thereof; Polyethylene oxide; Polyethylene glycol; Polyvinylpyrrolidone; Polyacrylic acid; Polymethacrylic acid; Polyethylene glycol derivatives; Polypropylene oxide or derivatives thereof; Copolymers of poly (ethylene glycol) and polyethylene oxide; Polyvinyl alcohol; Ethylene vinyl acetate; Cellulose or derivatives thereof; Polyimide; Hydrogels such as collagen, polypeptides, guar and pectin; Polypeptide peptides; Poly (meth) acrylates such as poly (2-hydroxyethyl methacrylate); Poly (meth) acrylamide; Polysaccharides; Zwitterionic polymers such as poly (phosphoryl choline) derivatives, polysulfobetaine, and polycarbobetaine; Amphoteric polyampholyte; ≪ / RTI > and polyethyleneimine. The hydrophilic coating preferably comprises at least one polymer having a tertiary amine functionality such as poly (2-ethyl-2-oxazoline).

In certain embodiments, the coating compositions used in the method of the present invention comprise one or more suitable surfactants to reduce surface tension. Surfactants include substances more well known as wetting agents, defoamers, emulsifiers, dispersants, leveling agents, and the like. Surfactants may be anionic, cationic and nonionic, and many types of surfactants are commercially available. Some coating compositions comprise at least one wetting agent. Other coating compositions may contain additional surfactants to perform additional effects.

Other suitable surfactants may also be selected. The amount and number of surfactants to be added to the coating composition will depend on the particular surfactant (s) selected but should be limited to the minimum amount of surfactant necessary to achieve wetting of the substrate without degrading the performance of the dried coating . In certain embodiments, the coating composition comprises 0.01 to 10 wt% surfactant, in some embodiments 0.05 to 5 wt% surfactant, and in another embodiment 0.1 to 3 wt% surfactant . The amount of surfactant present in the coating composition may range between any combination of these values, including the recited values. The use of coating compositions in the membranes of the present invention enables their use in separation systems without the need to pre-wet the membranes as is the case with isopropanol.

The microporous material may be attached to a support layer, such as a glass fiber layer, to provide additional structural integrity depending on this particular end use. Further, arbitrary stretching of the continuous sheet may be performed immediately in at least one stretching direction during or after any step immediately after the extrusion in step (ii). For example, in the production of the ultrafiltration membrane of the present invention, the process of making the microporous material may allow for an upper range of pore size of ultrafiltration by stretching the continuous sheet during calendering. Typically, however, in the production of the ultrafiltration membrane of the present invention, the process of making the microporous material does not include a stretching step.

The microporous material produced as described above can remove (ultrafiltrate) the particulate from the fluid stream in the size range of 0.005 to 0.1 micron and remove (microfiltrate) the particulate from the fluid stream in the size range of 0.05 to 1.5 micron Which is suitable for use in the microfiltration and ultrafiltration membranes of the present invention. Such membranes also serve to remove molecular contaminants from the fluid stream by adsorption or by physical removal according to molecular size.

The membranes of the present invention can be used to separate suspended or dissolved materials from fluid streams, such as removing one or more contaminants from a fluid (liquid or gas) stream or concentrating the desired components in a depleted stream Lt; / RTI > This method typically involves contacting the stream with the membrane by passing the stream through the membrane. Examples of contaminants include toxins such as neurotoxins; heavy metal; hydrocarbon; oil; dyes; Neurotoxin; medicine; And / or pesticides. A fluid stream (which is a fluid such as a stream of water, which may be a liquid or a gas) is generally at least 25 psi, for example 1 to 10000 gal / (ft ² day) (GFD) at 25 psi without the use of a pre- Passes through the membrane at the flow rate. The ultrafiltration membrane may exhibit a water flux rate of greater than 100 GFD, preferably greater than 150 GFD, and a molecular weight cut-off of 100 to 500,000, while the microfiltration membrane may exhibit greater than 300 GFD May represent over 500 GFD of runoff. The films of the present invention exhibit a Gurley number of less than 2000 seconds.

A coated film comprising a microporous material coated with a hydrophilic coating composition exhibits a water contact angle of less than 70 °, typically less than 30 °, more typically less than 10 °.

Example

In Part I of the following examples, the materials and methods used to prepare the microporous sheet material are described. In Part II, the methods and conditions used to elongate the microporous sheet material are described. Part III describes coating formulations and methods used to coat microporous sheet materials. Physical properties of the Examples (coated) and Comparative Examples (uncoated) are shown in Part IV.

part  I - Preparation of microporous sheet material

The dry components of Example 1 were individually fed into an FM-1300 Littleford plow blade mixer with one high-strength chopper style mixing blade in the order and amount specified in Table 1 . The dry ingredients were premixed for 15 minutes using only a plow blade. The process oil was then pumped through the spray nozzle into the dual diaphragm pump over a period of about 45 to 60 seconds at the top of the mixer with only the plow blades running. Then, the high-strength chopper blade was run with the plow blade, and then mixed continuously for 30 seconds. Turn off the mixer and sweep down the inside of the mixer so that all the ingredients are evenly mixed. The mixer was run again with both the high strength chopper and the plow blades in use and then continued to mix for an additional 30 seconds. The resulting mixture of dry ingredients was extruded and then calendered in sheet form as described below. The weight loss in the weight feed system (K-tron model # K2ML T35D5) is achieved by feeding the mix into a 27 mm twin-screw extruder (Leistritz Micro-27 mm) Respectively. The extruder barrel consisted of eight temperature zones and one heated adapter for the sheet die. The extrusion mixture supply port was located just before the first temperature zone. The atmospheric vent was located within the third temperature band. The vacuum vent was located within the seventh temperature band.

The mixture was fed to the extruder at a rate of 90 g / min. Also, in some cases, additional processing oil is injected in the first temperature zone to achieve the desired total oil content in the extruded sheet.

Examples 2 and 3 were prepared using an extrusion system, which is a production scale, extruded and then calendered in the form of a final sheet. The version of the system is similar to the apparatus and procedure described above for Embodiment 1 except for the size of the apparatus. The oil contained in the extruded sheet (extrudate) exiting the extruder is referred to herein as the extrudate oil weight fraction, which is based on the total weight of the sample. The arithmetic mean of the extruded oil weight fraction for all samples was 0.57. In each of Examples 1, 2 and 3, the residual oil was removed using a 1,1,2-trichloroethylene oil extraction process.

Table 1: Microporous membrane sheet formulation

¹ Tycho and is commercially available from the Corporation reported to have a molecular weight of about 9,200,000 g / mol, polyethylene, ultra high molecular weight (UHMWPE).

² High molecular weight polyethylene (HOPE), commercially available from Total Petrochemicals.

³ Settled silica commercially available from PPG Industries, Inc.

⁴ Calcium-zinc stearate lubricant, commercially available from Ferro.

⁵ A processing and heat stable blend of antioxidants commercially available from BASF.

Process oil commercially available from ⁶ PPC Lubricants.

part II  - Stretching  Preparation of sheet microporous material

Stretching was carried out by Parkinson Technologies, Inc. using a Marshall and Williams biaxially oriented plastic processing system. The machine directional orientation (MDO) stretching of the material in Part II is accomplished by heating the microporous sheets of Examples 2 and 3 and then machine-stretching it on a series of rollers maintained at the temperatures listed in Table 2 below Respectively.

The transverse orientation (TDO) stretching can be accomplished by heating the sheet produced after MDO stretching according to the temperature conditions listed in Table 2 below, then placing the two horizontal chain tracks (or transverse direction) on a tenter frame composed of a horizontal chain track. The combination of MDO and TDO conditions provided biaxial stretching of the material.

Table 2: Microporous sheet stretching conditions

part III  - Hydrophilic coating formulation

a) Preparation of hydrophilic coating:

Hydrophilic Coating Examples A, B and C were prepared according to the components and amounts listed in Table 3 below. The first component of the example was dissolved in a specified amount of deionized water with vigorous stirring. When completely dissolved, butanol was added followed by Pluronic 17R2. The coating solution was gently agitated for at least 30 minutes before proceeding.

Table 3: Hydrophilic coating formulations

¹ molecular weight 50,000, commercially available from Sigma-Aldrich.

² Chitosan extracted from shrimp shell, practical grade, marketed by Sigma-Aldrich.

³ Polyvinylpyrrolidone with an average Mw of 360,000, commercially available from Sigma-Aldrich.

⁴ block copolymer surfactant, commercially available from BASF Corporation.

b) Coating procedure of microporous material:

The microporous material described in the previous example was cut into 12 in ² (in ² ) sheets. The hydrophilic coating composition was applied by immersing the microporous material of the preceding example in a Pyrex dish containing a sufficient amount of hydrophilic coating so that the sheet was completely submerged. The sheet was immersed in a hydrophilic coating for about 5 minutes. Subsequently, the sheet was removed from the solution, and then excess coating solution was dropped thereon. The coated microporous material was then clamped to an aluminum frame equipped with a gasket to prevent shrinkage of the film during drying. The frame containing the film was then dried in an oven at 95 DEG C for 15 minutes. The stretched microporous material of Example 4 was coated in this manner with the coating solutions of Examples A, B and C, respectively. The stretched microporous material of Examples 5 and 6 and the undyed microporous material of Example 1 were coated with the coating formulation of Example A.

part IV  - Characteristics:

The stretched microporous material of Examples 4, 5 and 6 and the undrawn microporous material of Example 1 were tested for properties and permeability when a hydrophilic coating was applied and when not applied.

Table 6 shows the differences between the microporous materials of Example 4 with and without a hydrophilic coating composition. Tables 7 and 8 illustrate the permeability of various microporous materials with and without a hydrophilic coating composition. These properties were measured using the methods described below:

a) Thickness was measured using an Ono Sokki thickness gauge EG-225. The reported thickness is the average of 9 measurements.

b) Porosity was measured using a Gurley Precision Densometer, model 4340, manufactured by GPI Gurley Precision Instruments, Troy, New York.

c) The maximum elongation at break and tensile elongation energy for the samples were measured according to the procedure of ASTM D-882-02. The orientation of the samples was tested so that the stresses were applied in the machine direction ("MD") and the transverse direction ("TD") as described in Part II.

d) The contact angle was measured on a VCA 2500XE video contact angle system commercially available from AST Products, Inc., using 1 microliter (ul) of ultra pure water.

e) Water flux testing was carried out using a Sepfa CF II cross flow test cell device (Sepa CF II, available from Sterlitech Corp., Kent, Wash.) with a membrane effective area of 140 cm 2, cross flow test cell apparatus.

f) Water intrusion pressure was measured on a circular sample with an area of 90 cm 2. The samples were sandwiched in filters with one end closure provided by Stelltech Corporation, Kent, Wash. 100 mL of water was placed on top of the sample. The pressure was applied while increasing the pressure by 5 psi, while maintaining the pressure increment for 15 minutes. The test pressure was recorded when the first drop water was visualized through the sample.

g) Pore volume: The pore volume, expressed in% by volume, is measured according to the following equation:

Porosity = 100 (1 - d ₁ / d ₂ )

Where d ₁ is the density of the sample measured from the same weight and sample dimension and d ₂ is the density of the solid portion of the sample measured from the sample weight and the volume of the solid portion of the sample. The volume of the solid portion of the sample is measured using a stereo peak furnace (Quantachrome Corporation) according to the attached operating manual.

Table 6: Physical properties of uncoated microporous material and hydrophilic coated microporous material

Table 7: Permeability of uncoated microporous material

^* Undetectable volume observed after 30 minutes at 20 psi

Table 8: Permeability of microporous materials with hydrophilic coatings

Although specific embodiments of the present invention have been described for illustrative purposes, those skilled in the art will readily appreciate that various modifications of the details of the present invention may be made without departing from the scope of the invention as defined in the appended claims. I will know.

Claims (17)

What is claimed is: 1. A coated filtration membrane comprising a coated microporous material,
Wherein the coated microporous material is a < RTI ID = 0.0 >
(a) a polyolefin matrix present in an amount of at least 2% by weight,
(b) a finely divided particulate substantially water-insoluble silica filler distributed throughout the matrix, wherein the filler comprises about 10% to about 90% by weight of the coated microporous material substrate;
(c) at least 20% by volume of a network of interconnecting pores communicating throughout the coated microporous material, and
(d) at least one coating composition applied to at least one surface of the film to adjust the surface energy of the film
Wherein the coated filtration membrane exhibits a water contact angle of less than 70 °,
Coated filtration membrane. The method according to claim 1,
Wherein the coated filtration membrane exhibits a water contact angle of less than 30 [deg.]. The method according to claim 1,
Wherein the coated filtration membrane exhibits an initial water flux of at least 1 GFD at 25 psi without the pre-wetting agent applied. The method according to claim 1,
Wherein the polyolefin matrix comprises an essentially linear ultra-high molecular weight polyethylene having an intrinsic viscosity of at least about 18 deciliters per gram, an essentially linear ultrahigh molecular weight polypropylene having an intrinsic viscosity of at least about 6 deciliters per gram, Lt; RTI ID = 0.0 > polyolefin. ≪ / RTI > 5. The method of claim 4,
Wherein the matrix further comprises high-density polyethylene and / or low-density polyethylene. The method according to claim 1,
Wherein the membrane is an ultrafiltration membrane and the average pore size is less than 0.1 micron. The method according to claim 6,
Wherein the coated microporous material exhibits a molecular weight cut-off of 100 to 500,000. The method according to claim 1,
Wherein the membrane is a microfiltration membrane and the average pore size is greater than 0.1 micron. The method according to claim 1,
Wherein the coated microporous material has a thickness in the range of 0.7 to 18 mils (17.8 to 457.2 microns). The method according to claim 1,
A coated filtration membrane, wherein the coating applied to the surface of the material comprises a hydrophilic coating. 11. The method of claim 10,
Wherein the hydrophilic coating is selected from the group consisting of polyoxazoline, triblock copolymers based on poly (ethylene glycol) -poly (propylene glycol) -poly (ethylene glycol), polyethyleneimine, polyamide, oxidized polyethylene or derivatives thereof, polyethylene oxide, Polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyethylene glycol derivatives, polypropylene oxide or derivatives thereof, copolymers of poly (ethylene glycol) and polyethylene oxide, polyvinyl alcohol, ethylene vinyl acetate, cellulose or (Meth) acrylate, a poly (meth) acrylamide, a polysaccharide, a zwitterionic polymer, a polyampholyte, or a derivative thereof, or a derivative thereof, a collagen, a polypeptide, a guar, a pectin, a polyimide, a polypeptide, ), ≪ / RTI > and polyethylene imine. . 11. The method of claim 10,
Wherein the hydrophilic coating comprises at least one polymer having a tertiary amine functionality. The method according to claim 1,
Wherein the silica (b) has a surface treated with at least one of polyethylene glycol, carboxybetaine, sulfobetaine and polymers thereof, mixed atomic molecules and oligomers and polymers thereof, positively charged residues, and negatively charged residues. Filtration membrane. The method according to claim 1,
A coated filtration membrane in which the silica (b) is surface-modified with functional groups. The method according to claim 1,
Further comprising a support layer to which said microporous material is attached. The method according to claim 1,
Wherein the weight ratio of silica: polyolefin is in the range of 0.5: 1 to 10: 1. The method according to claim 1,
Wherein said microporous material exhibits a Gurley number of less than 2000 seconds.