POLYAMIDE MICROPOROUS MEMBRANE, PROCESS FOR ITS PREPARATION.

Claims 1. surface-modified polyamide membrane, skinless, hydrophilic, microporous, in alcohol, characterized in that it comprises a polyamide resin hydrophobic, insoluble in alcohol, having a ratio ch2: NHCO group between the ch-methylene groups, amide groups and NHCO group which is in the range of 5: L to 7:1, said membrane AF) having its

propriëtés

surface can be substantially influenced by the cationic groups are quaternary ammonium polymer of a changing

surIhce

lo cationic quaternary ammonium thermoset

confërant

to the membrane potential

zëta

positive in alkaline medium and (b.) requesting a duration of Li) min or less after the beginnings of filtration to form water having a

résistiçité

i4 of mega ohms cm in test conditions are resistivity, membrane according to claim 2. ls I-la, characterized in that it is traversing a surface Å the other through pores of substantially uniform size and

tarme

.3. the membrane of claim l, characterized R4II ' Eliel is traversing a surface to

rautre

through pores of conical shape, wider on one surface of the sheet and narrowing toward the stepped: CEA opposite of the membrane.4. membrane according to one of claims 1 to 3, characterized in that the polyamide resin is a polyhexamethylene

adipatolde

.Membrane according to claims 1 to 4 trawl, characterized in that it comprises 80 to 99.9% of a polyamide resin insoluble hydrophobic alcohol having a ratio of 5:1 to 7:1 between groups

CHz

NHCO group and the groups and 20 to 0.1% of a cationic surface modifying

polymér

cents, of quaternary

ammouium

, thermoset, the surface properties of the membrane is substantially determined by the groups of the cationic quaternary ammonium

polymëreconférc

which alter the membrane in a positive zeta potential in alkaline medium.6. use of a plurality of membranes according to trawl of claims I to 5 as a multilayer filter sheet.7. method of preparing a polyamide membrane easily wetted by water according to claim 1, characterized in

quï

! comprises the following steps:(1) a solution is prepared casting comprising (has) casting a resin mixture composed of (has) a polyamide resin in alcohol having a ratio of CH: NHCO group between the methylene groups and the groups

umideCHz

NHCO group which is within

lïntervaIle

of 5:1 to 7:1, and (d) a polymer

eationique

, water-soluble, quaternary ammonium, thermosetting, modifying

surthce

of the membrane, and (d) a solvent in which said resin mixture is soluble casting:(2) causing the nucleation of said casting dope by controlled addition of a non-solvent of said resin blend to be cast under conditions

contrõ

[SEA concentration, temperature, rate of addition of and degree of agitation, to obtain a visible precipitate particles of the mixture

rësineux

casting, thereby forming a casting composition:(3) casting said composition is spread on a support whereon SSs this forms a film:(4) bringing the film casting said composition Angstroms contact and diluted with a liquid non-solvent for the resin mixture Angstroms casting, liquid which comprises a mixture of liquid solvent and liquid non-solvent, thereby causing the precipitation on the support of O said resin mixture to flow therefrom to be cast in the form of a polyamide membrane thin, skinless, hydrophilic, surface modified,

microporcuse

; 5) is

lare

the membrane to remove solvents, and (6) drying the membrane.8. method according to claim 7,

caraetérisé

in that the particles of the resin mixture to flow precipitated are redissolved before spreading the composition on the support casting.9. method according to claim 7, characterized in that the particles of the resin mixture Angstroms casting precipitated are filtered before spreading of the composition to be cast on the support.Method according to claims 7 to 9 trawl, characterized in that the polyamide resin is a

polyhexaméthyléne

-to-

ãdipamide

, a pol - epsilon-caprolactam, or a polyhexamethylene

sébaçamide

.11. Method according to one of claims 7 to 10, characterized in that the DC xSy .,

tëme

solvent mixture

résineu

: theS casting comprises formic acid, and the non-solvent added to cause

nueléation

is water.12. method according to one of claims 1 to 7 the I, characterized in that the solvent of the system

résineu

: theS casting comprises formic acid and DC water.!3. method according to one of claims 7 angstroms 12, characterized in that the

polsmère

modifies the surface of the membrane is a polymer or a polyamine-

ëpichlorhydrinepolymëre

of polyamidoamine polyamino

épichlorh3drine

.14. Method according to one of claims 7 angstroms 13, characterized in that the casting composition is

étalëe

continuously on the support, the film of the composition Angstroms cast is continuously immersed in a bath of the!

iquidc

non-ground ', ant and the bath is maintained substantially constant composition Angstroms non-SO2!efore and solvent by addition of the non-solvent in an amount sufficient to compensate for the diffusion of the solvent into the bath angstroms from the film of the composition to be cast.14

Procédë

claim, characterized in that the support consists of a porous fabric to open structure which is wetted and impregnated by the casting composition with formation of a pellicle membrane wherein the porous fabric is embedded and constitutes a part of the film.The present invention relates to a microporous membrane of polyamide, preparation method thereof.Used from a certain time microporous membranes for filtering fine particles contained in gaseous and liquid media. In the Patent of the United States of America no. 4,340 479, a method for preparing microporous membranes of polyamides having certain advantageous features filtration. The membranes

pïépar

+ is checked by this method are hydrophilic, they have distributions narrow pore sizes and fineness of pores which can go up to about 0.04 microns. For many filtration requirements, these membranes are very effective. However, for some fine particles, for example particles of diameter substantially smaller than 0.1 microns to, they are ineffective. The reasons for this inefficiency is in relation to the filtering mechanisms themselves.The function of a filter is the removal of suspended particles and passage of the clarified fluid. A filter membrane can cause the clarification of a fluid by different mechanisms. The particulate material may be separated by a mechanical sieving where all particles larger than the pore diameter of the filter membrane are removed from the fluid. With cc mechanism, the filtration efficiency is

contrõlée

by the relative size of the impurity and the pore diameter of the filter, and the efficient removal of particles very small, for example size

infërieure

to O, I-micron diameter, therefore requires filter membranes it minute pore sizes.Gold, these filter membranes Å in fine pores tend to have undesirable properties: a high pressure drop through the filter membrane, a reduced capacity for contaminants and a

dnrëe

service curtailed.A filter may also remove suspended particles by absorption on the surfaces of the filter membrane. Particulate removal by this mth "

mismecontrõlée

is by surface features of (1) the particles in suspension and (2) the filter membrane. Most of the suspended solid substances which are passed commonly Angstroms filtering off are negatively charged in the aqueous

systëmes

. This feature has been recognized for a long time in a TES processing operations of the ADCs in which agents are used cationic

fioculants

, a charge opposite that of the suspended material, to improve

efiícacité

sedimentation during the water clarification.The theory of the colloidal stability may be used to predict the interactions of particles and surfaces carrying LOs electrostatic charges. If loads of suspended particles and the surface of the filter membrane are of the same sign, with potentials greater than about 20

zëta

MVs, a TES mutual forces of repulsion will be sufficient power

empëcher

capture by adsorption. If the zeta potentials STD suspended particles and the surface of the filter membrane are low is more preferably of opposite sign, the particles will tend Way adhering to surfaces of the filter membrane with high capture efficiencies. Most particle suspensions encountered in industrial practice have potential

zèta

negative. As result, a TES microporous filter membrane characterized by potentials

zëta

positives are capable, in a large number of industrial applications, to remove particles of smaller dimensions than the

diamëtres

membrane pore by the mechanism of the electrostatic pickup. 2s believed properties advantageous hydrophilic polyamide membranes Patent of the United States of America no. 4,340 479 are due in part to the high concentration of amine end groups of the polyamide acid and

earboxylique

on exposed surfaces of the membrane. It is also believed that the position of the groups is the cause for the unusual profile of the zeta potential as a function of pH for these membranes. This profile, positive at pH values below 6.5, becomes negative in alkaline medium. Therefore, the membranes have a limited capacity to filter very fine particles negatively charged in an alkaline medium.By altering the surface characteristics of the hydrophilic membranes

déerites

in Patent of the United States of America no. 4, 340479 for example and by ensuring a zeta potential in the alkaline region strongly positive, it would increase significantly the range of use of these materials in the filtration.The present invention relates to a polyamide membrane surface modified, skinless, hydrophilic, microporous, in alcohol, characterized in that it comprises a polyamide resin hydrophobic, insoluble in alcohol, having a ratio goosefoot: NHCO group between the methylene groups and the groups

umide

ch2 4s NHCO group which is within!' 5:1 to 7:1 interval, said membrane (Al having its surface properties can be substantially influenced by the TES quaternary ammonium cationic groups of a polymer

modiñant

quaternary ammonium cationic surface thermoset, providing the membrane with a positive zeta potential in alkaline medium, and (d) requesting a duration LO min or less after the beginnings of filtration to form water having a resistivity of 14 megohms/cm in test conditions are of resistivity.The membranes surface-modified according to the invention, with their potential

zëta

strongly positive, may Give use for their LC ' - SSs

ñcacité

filtration greatly enhanced in a large pH range and with a wide variety

dïmpuretés

, including particulates,

extrëmement

negatively-charged fine particles, bacteria and endotoxins. The membranes of the invention are also capable of delivering ultra-pure water quickly after the beginnings of the filtration. This ability to deliver a high purity outgoing water, free of microparticles and ionic impurities, the subjection of the

lïnvention

are particularly advantageous in the filtration of aqueous liquids used in the manufacture of microelectronic

euxmëmes

. 6s also disclosed is a method of preparing a polyamide membrane easily wetted by water, which is characterized in that it comprises the following steps:656,887 (1 a solution casting comprising (a resinous blend AI casting consisting of (ai a polyamide resin in alcohol at a ratio (ch2: NHCOC1) ch-methylene groups, amide groups to NHCO group in the range of 5:1 to 7:1, and (d) a cationic polymer, water-soluble, quaternary ammonium, thermosetting, modifying the surface of the membrane, and (d) a solvent in which said resin mixture is soluble casting; (2) the OH induces nucleation of said casting dope

contrõlée

by adding a non-solvent with respect to the resin mixture to flow under conditions

eontr61ées

concentration, temperature, rate of addition of and degree of agitation, to obtain a visible precipitate particles of the resin mixture to flow, thereby forming a casting composition; (3) said casting composition is spread on a support, thereby forming thereon a film; (41 is contacted and is diluted film of the composition to be cast with a liquid non-solvent with respect to the casting resin mixture, this liquid non-solvent consisting of a mixture of the solvents and nonsolvent fluid, thereby causing the precipitation on the support of the resinous mixture to flow from the casting composition, in the form of a polyamide membrane thin, skinless, hydrophilic, surface-modified and microporous; (5) is

lare

the membrane to remove the solvent, and (6) drying the membrane.The membranes of polyamides and surface-modified alcohol insoluble according to the invention have the unusual property of being hydrophilic,

c'est

H-say they are easily wetted by water, have pore sizes (also referred to as a pore diameter) of 0.04 to 10 (preferably from 0.1 to 5 micron) or more, potentials

zëta

modified,

c'est

i.e. zeta potentials strongly positive in alkaline medium, filtration efficiencies ranging from molecular dimensions (pyrogenic) up to particles larger than the pore diameter, and consequently they have considerable advantages as filter media, in particular for the

prêparation

sterile filtrate bacterial standpoint, as well as in filtration of water purity suitable for use in making haunts microelectronic, due to their ability to deliver a filtrate

ukrapur

microparticles and free of ionic impurities.The polymers or resins by modifying the surface of the membrane that may be used for preparing the membranes of the invention are water-soluble

cafioniques

polymers, quaternary ammonium, thermosetting. Preferred polymers in this class are the polyamide resins!polyamidoamine epichlorohydrin epoxy functionalized. Polyamine resins-epichlorohydrin epoxy functionalized are particularly appreciated.Other features and advantages of the invention shall become apparent from the detailed description given below with reference to Figure of the attached drawing single which graphically represents the proportion in % of polymer surface modifier that needs to be added depending on Da and time for obtaining water outflow port having a resistance of megohms 14!cm with a surface-modified membrane according to the invention.The membranes of polyamides Patent of the United States of America no. 4, 340479 are prepared from polyamide resins insoluble in alcohol having a ratio of 5:1 to

lïntervalleméthylèneiamide

in 7:1, as the membranes surface-modified according to the invention. From membranes of this group, examples of copolymers

l'hexaméthylène

-diamine and adipic acid (a nylon 66), copolymers

l'hexaméthylène

-diamine and sebacic acid (a nylon 610), homopolymers of poly-caprolactam (a nylon 6) and copolymers of hexamethylenediamine and azelaic acid (a nylon 69). Preferred nylon 66.In the process of preparing membranes Patent of the United States of America no. 4,340 479, the polyamide resin is dissolved in a solvent such as formic acid, and adding a nonsolvent such as water under conditions

contrõlées

agitation so as to cause nucleation of the solution.656,887 causing in-nucleation of the polyamide solution, a visible precipitate is formed. This precipitate can be redissolved in part or completely. Preferably DCs, ] in ES visible particles which do not need to be filtered from the

redissolvent

system, e.g. using a filter l0 micron, before pouring the solution had casting composition having undergone the nucleation.The solution or casting composition having undergone the

nneléation

is then cast onto a support, for example a porous sheet of polyester fabric or a non-porous polyester sheet, in the form of a film: W film l0 solution is then brought into contact and diluted by a liquid non-solvent which is a mixture of a solvent and a non-solvent of the polyamide resin.A nonsolvent liquid preferred in both

lïnvention

and in the Patent of the United States of America no. 4,340 479 consists of a solution of water and formic acid. In the present invention, !' formic acid is preferably present in an amount from approximately 35 to 60% by weight. The polyamide resin then precipitates from the solution, forming a sheet of hydrophilic membrane on the support, sheet which can Give washed for removal of the solvent. The membrane can then be peeled from the support and dried or, if the support is porous, it may be incorporated into the membrane and serve as a permanent support, in which case it is dried with the membrane. If the holder is to be incorporated into the membrane, II is to be porous and is to be wetted and impregnated with the casting composition: it may be for example a polyester sheet fibrous and porous open structure. By appropriate control operation variables, obtainable membranes with pores extending therethrough to uniform sizes and shapes. Conversely, if desired, can be conical shaped pores, wider on one surface of the sheet and shrunk when moved to the opposite surface of the sheet.The same general procedure described above is followed in the preparation of the surface-modified membranes according to the invention, except that the modifying polymer surface of the membrane used in the present invention are combined with the resin of po3s

lyamide

and that the resulting solution to flow combined with a polyamide/modifying polymer, to form the composition

nuclëafion

after casting, is cast into a, leading to novel microporous filter having novel properties that extend the field of use of membranes

raieroporeuses

DCs polyamide.It is believed that the novel

propñétésñltrantes

membranes prepared by the method of Patent of the United States of America no. 4,340 479 above result in high concentration portion of the amine end groups of the polyamide acid and

carboxyliquc

on!in ES surfaces of the membrane. These amine and carboxylic acid functions existing on the membrane surfaces lead to unexpected

propñétés

of the membrane, such as a profile unusual zeta potential as a function of pH and hydrophilicity,

c'est

-to-

fidire

that the membrane is wetted easily by water, commonly with complete penetration in 3 s or less, preferably 1 s or s0 least, immersion within the ADC.As has been already indicated, it was found that the membranes surface-modified according to the invention, novel and unexpected properties filtration, could be prepared by the general procedure described in the Patent of

Etatsss

States

Améñque

no. 4,340 479 above, but with the addition of small proportions of selected polymers, modifying the surface of the membrane, to the solutions giving by casting the polyamide membrane. As a result, by the casting method in common tip

Finvention

, easily and economically prepared microporous membranes of polyamides, hydrophilic, surface-modified, having a potential

zëta

strongly positive in alkaline medium, containing low proportions of materials

extractiblcs

, and having the capability of delivering ultrapure water, free of microparticles of ionic impurities and, shortly after the beginning of the filtration, as is required in the manufactures

mieroélectroniques

.It has been found that the addition of a low level, e.g. 1% by weight, relative to the polyamide resin, the polymer

moditìant

the stepped: CEA of the membrane to the solution casting of the membrane leading to hydrophilic microporous solid supportand membrane features whose surface properties were substantially determined by the modifying polymer. It is the capacity of a relatively low the modifier polymer membrane surface to adjust!in ES surface properties of the membranes of the present invention brings SSO diaphragms!in ES

caractëristiques

advantageous searched. Therefore, the filtration characteristics and behavior

supefficiel

physicochemical these membranes are

contrõlésFaide

to a relatively low proportion of the modifying polymer.The surface-modified polyamide membranes prepared by the process of casting in common (1) share certain characteristics with both (2) membranes of polyamides base prepared by the same general method of casting, but without the modifier polymer present in the solution casting, and ¢ 3) the membranes of polyamides base prepared as the membranes (2) above but which have

æté

then coated with a polymer or cationic resin by contacting the polyamide membrane base finished with a solution of polymer or cationic resin.The three types are skinless, hydrophilic (as in the present

demåndedèfini

and in the Patent of the United States of America mentioned no. 4340479} and microporous. Each of these types has filtering characteristics advantageous to

Iëgard

fine particles, derived in part from the fineness of the pores and narrow distributions of pore sizes. However, unlike the membranes (2) polyamide base above, the surface-modified polyamide membranes (1) and membranes of coated polyamide (3) have a positive zeta potential in alkaline medium, thereby widening the field of use of membranes (! (3) j and.The surface-modified polyamide membranes according to the invention and!in ES membranes (2) polyamide base la also have capability of delivering of!' ultrapure water, free of microparticles and ionic impurities, soon after the beginning of the filtration, conversely, coated polyamide membranes (3) have smaller this

capaeitë

at the point where it is found in membranes (1} or C2 " this capability as

dëcrite

in detail below is very advantageous in!in ES

íabric

ing microelectronic applications. Since only the surface-modified polyamide membranes (11 according to the invention have the unique combination of a positive zeta potential in alkaline medium and the

capacitëdéIiwer

of ultrapure water, free of microparticles and ionic impurities, soon after the beginning of the filtration, the advantage of this class of membranes is manifest. It is believed that the properties of the membranes are highly advantageous result from the novel process wherein the

prëparationpolymëre

modifying becomes part of the overall structure of the membrane. The Li capacity

nlembranes

preparing such a direct way, clean, efficient and economical increases their interest.The polymers or resins by modifying the surface of the membranes (sometimes called hereinafter "

poIymères

modifiers") that can be used in the invention are cationic polymers,

hydrosoluNes

, quaternary ammonium, thermosetting. Polymers preferred modifiers are those which undergo cross-linking reaction by reacting the epoxide groups. [polymers or resins. AE

eationiques

epoxy functionalized lead in general to surfaces modified fillers which angstroms, by converting the crosslinked state under the action of heat, are resistant and chemically

mécaniqnementlëgard

of a broad range of chemical environments.The cationic polymers or thermosetting epoxy functionalized epoxide are also preferred because it is believed that there is favorable interactions between the amine and carboxylic acid end groups of the polyamide, GHG amine functions and carboxylic acid functions are commonly known to react effectively with!in ES epoxy-functional polymers. It is believed that!in ES amine and carboxylic acid groups of the polyamide resin are reactive with

ëpoxyde

the modifier polymer.Although it is believed that la reaction of these groups 656,887 occurs in the membrane structure, the OH

peuse

as the nature of the method of forming the membrane causes a preferential orientation of the modifying polymer to the membrane surfaces formed. It is to say that the spigot is the operation for the DC casting in common, according to the invention, the polymer

modisdëterminecaractëristiques

relies on the membrane surface. Further, it is believed that the reaction groups leads to an intimate connection of the modifier polymer and DC polyamide resin to form an integral structure resulting in a decrease in the amount of extractable material, to a more homogeneous LOs surfaces and to increased overall stability of the membranes.Another advantageous feature of modifying polymers is in relation to the nature of the cationic charge. Because their cationic nature is due to the presence of quaternary ammonium groups, or maintain their positive charge at acidic pH ls neutral and alkaline, it was surprisingly found that during the operation of forming the membrane, the smaller fractions of modifying polymer added appeared Give preferably oriented so as to lead to membranes having surface features that are substantially determined by the modifying polymer. It is believed that this result reflects both the operation of forming the membrane and the hydrophilic nature of polymeric modifiers. It is believed that the combination DCs the

hydropbilie

, the apparent strong interaction with the end groups of the polyamide and the casting operation in common is responsible for modifying polymers apparent preferential orientation toward the surface of the membrane.It has also been found that, although the polymeric modifiers are very soluble in the ADC, they are not removed from the composition to flow into the liquid non-solvent used to precipitate the casting resin system. Apparently, the strong interaction of the

pob

' mother changing with the end groups of the polyamide coupled with the preferred orientation of the modifying polymer to the membrane surfaces (both pore surfaces and outer surfaces), perhaps under the influence of the nonsolvent liquid, combine to provide a membrane whose surface properties are substantially determined by the TES cationic quaternary ammonium groups of the modifying polymer. This unexpected result is

trës

advantageous.The epoxy functional resins or epoxy-based

préférente

lie in two classes: the TES resins of polyamidoamine/polyamino

èpichlorhydrine

tees and polyamine-epichlorohydrin resins. the first are reaction products of epichlorohydrin with polyamides containing in the backbone of primary amines, secondary and tertiary. Representative examples of this class of 4s products are described in the patents of U.S. no. 2, 926154, 3,332 901, 3,224 986 and 3,855 158.The water-soluble polymers, non-

collNdaux

, C.

tioniques

thermosetting of commerce that preferred is the class of polyamino epichlorohydrin resins polyamidoamine/tees series resins are trademarks

Kymene

557 and

Polyeup

Hercules Viscosity of self-dealer. It is believed that these resins are prepared by reacting epichlorohydrin with low molecular weight polyamides containing amino groups in the polymer backbone. The reaction products have been described as containing methanesulphonic

monium

quaternary groups present as azetidinium ions which are 4 membered cyclic structures. The

Kymene

557 and resins of the series

Polycup

have been described as adjacent chemically and by the structure, but with different molecular weights.The polyamine-epichlorohydrin are condensation products of polyamines such as polyalkylene polyamines or their precursors with!' epichlorohydrin. They differ from the polyamidoamine/polyamino epichlorohydrin resins in that they do not contain amide-

corame

membered part of the polymer backbone. Compositions of this type are disclosed business (1) in the Patent of the United States of America no. 3,885 158 which describes polymers prepared by reacting

Iëpichlorhydrine

with the condensation product of polyalkylene polyamines and ethylene dichloride, and (2) in the Patent of the United States of America no. 3,700 623 which describes polymers prepared by reacting epichlorohydrin with a

polydia

!

lylméthylamine

, among the compositions of the first type agenda such quotas, include of the product trademark

Santores

31 of the Monsanto Inc. and among the products of the second type the brand name product in a resin r4308 (Hercules Viscosity Inc. in).Most preferred is a TES triggerable epoxy functionalized entering the class of polyamine-epichlorohydrin resins and which bear quaternary groups to status is crosslinked. The fact that the TES quaternary groups remain in the resin when cured is important since II has an influence on pH range in which the membrane can maintain a positive zeta potential. A quaternary ammonium group is cationic in nature: P-R-thus, its positive charge is independent of pH

Fenvironnemeut

. The products in a resin r4308

Santores

and 31 each carry quaternary ammonium groups in the crosslinked state and have a positive charge by alkaline pH.A large number of polymers with modifying requires activation.To impart

rësines

better storage stability and extended shelf life prior to use, is disabled

chimiquemcnt

epoxide groups to

empëcher

a premature cross-linking of these

polymèrcs

. As a result, before using these polymers, are necessary in order to pass

lëtat

thermosetting reactive epoxide groups by regeneration. Usually, the activation comprises adding a sufficient amount of sodium hydroxide solution to a solution of the polymer to convert inactive

chimiquemeut

shape chlorohydrin inoperative to the form epoxide crosslinking. The amount, in parts by weight, of caustic soda per part by weight of the

polymëre

varies with the product and is indicated by the manufacturer. Complete activation is generally obtained in 30 minutes.The preparation of membranes according

lïnventioncontrõlées

is carried out under conditions, including adding the non-solvent, for example water, to a solution of the polyamide and the modifying polymer, ICs

contrõle

of the constituent concentrations, monitoring the

tempërature

and control of agitating the system aimed at causing the desired level of nucleation.The detailed discussion given in Patent of the United States of America no. 4,340 479 mentioned about the relationship between the parameters mentioned above is applicable generally to the present invention and thereby not

rëpétée

.The manner and the rate of addition of the non-solvent to cause nucleation is related to other variations such as intensity of the operative

mëlange

, the temperature and concentration of the various components of the solution to be cast. The expression "casting dope" is used herein to designate the solution consisting of the resin system (has) to cast and (d) the solvent system. Preferably, adding the non-solvent is achieved through an orifice at a rate sufficient to produce a visible precipitate which, preferably, is redissolved subsequently in part at least. By maintaining the other parameters constant, will result castable compositions are provided having

caractéristiqucs

quite different in terms of pore size membranes resulting by varying the diameter of the orifice. Therefore, for each specific system, the desired degree of nucleation resulting from the rate of addition of the non-solvent and the configuration of the orifice will be established D nsec success by empirical testing.The addition

contrõlée

of the nonsolvent is described in detail in the Patent of the United States of America no. 4,340 479 above. Before the addition of the non-solvent for the induction of the enucleation, the casting dope is prepared from a resin system (has) casting consisting of (has) a polyamide resin in alcohol as described above, and (d) a modifier resin or polymer, and (d) a

systëme

solvent. The solvent system can consist of just a solvent casting of the resin system, for example formic acid. But the system solvent may also contain a certain proportion of vv non-solvent, e.g. water. The amount of solvent present in the solution non656 887 casting is always less than the amount needed to affect the stability of the solution.Before casting, is triggered

nueléation

solution casting by controlled agitation and controlled addition of the nonsolvent liquid. The amount and the rate of addition of the non-solvent are inspected at once that the intensity of the mixing by stirring.The advantage of] '. introducing a non-solvent system as part of the solvent to the

prëparation

solution casting is that the OH can maintain better control of the addition of the

nonsolvant

during initiation of the

nueléationquïl

because the O must be smaller proportions of non-solvent since there is already the non-solvent in the solution to be cast. As a result, it is possible to maintain better control of the rate of addition and obtain a product more

unilbrme

Angstroms DCs door any size desired.The resin system enjoying casting comprises (has) a resin DCs

polyumide

in alcohol having a ratio of 5:1 to 7:1

méthyIènearoide

. and Fb) a

polymêre

or modifier resin surface.All indications of portions and extend percentages by weight unless otherwise mentions.The relative proportions between the PolI) mother of modifier and the polyamide resin in the solution casting formed in first stage of the method, relative to the resin

polyamíde

, can vary from a higher level of 20 degrees' O in weight up to a level of 0.1% by weight

intërieur

,

c'est

fi e. 20 parts polymer modifier for 100 parts of polyamide resin polymer portion up to 0.1 s to 100 parts resin modifier for polyamide. The range generally preferred for addition of the modifying polymer is from about 1 to 5% by weight. Of level ": addition of L to 2.0% by weight has yielded results particularly

satislhisants

. It is believed that this addition moderate modifying polymer causes a change to substantially complete surface of the conducting membrane Å in a membrane whose characteristics DCs surface are substantially determined by the cationic quaternary ammonium groups of the

polymëre

modifying. As a result, from the viewpoint of efficiency of the membrane and DC production economy, the addition of about I to 2.0 degrees' enjoying the modifier polymer by weight, relative to the resin PO!

yamide

, constitutes the addition preferred, however that the polyamide resin layer is then

mëme

present in the solution to be cast in proportion of 10 to 18%, and the modifier polymer surface in proportion to 0.1 0.9% (by support for all components present in the solution).The amount of solvent present in the solution to be cast

lbrmée

in first stage of the method varies depending on the nature of the polyamide resin and Da-modifying polymer. In general, the amount of Glassware cleaner s ranges from 60 to 80% has (with respect to all components 4s in the solution).It should be noted that the solution angstroms (I) the casting comprises casting resin system,

c'est

fi e. the polyamide resin and the polymer or resin

modificar

, and (2) the solvent system,

c'est

fi i.e. a solvent for the resin system to be cast polyamide resin/polymer

modiñant

(e.g. formic acid) and, if desired, a minor proportion of a non-solvent with respect to the casting resin system angstroms (e.g. the ADC).The amount of non-solvent present in the. casting dope will be in all cases

intërieure

its amount in the nonsolvent liquid system (bath membrane formation) used to precipitate the resin system to be cast from the casting composition, the latter being the composition formed from the casting dope prepared initially by inducing nucleation in this solution and. preferably. elimination of visible particles of O

eomposition

formed. In

génërak

when the non-solvent is water, it will be present in the solution to be cast in a proportion of from 0, preferably at least 5%, preferably 10 to 20°ó, 30% by weight up to about (again relative to all components in the solution). 6s for a preferred solution to be cast, a polymer or resin polyamine-epichlorohydrin, preferably the commercial good

R430g

resin molding material, is present in the solution to be cast in proportion of 0.1 0.9 °, o has about, the polyhexamethylene adipamide is present in a proportion of 10 to 18° o. formic acid is present in a proportion of 75% 65 angstroms, and the ADC in proportion of 10 to 20°ó; all these parts extend by weight and relative Å in the total composition of the solution to be cast.The temperature of the composition to be cast is not critical as long as it is kept at a constant level. In

gënéral

however, a decrease in the temperature of the casting composition leads to a more

lbrtenuclëation

. [enjoying ' the mixing intensity in a

dèterminè

system is a function of a large number of variables related to each other. For any

déterminë

,

lïntensité

mixture may Give expressed P-R the speed of rotation of the stirrer. Such equipment can take many forms and many designs commonly used in the industry and it is difficult to give numerical values. As a result, it is required to empirical testing using the usual

vaïiables

establish the gap for mixing

eonvenvnt

intensities for a particular system. Thus for example, for a rotor of 6.35 cm operating at a flow rate of about 500 to 1500 g of solution per minute, the I! parts are required mixing rates in t'a cross " hitherto of 1500 angstroms 4600 rpm to obtain membranes with pore size in the

interre

hitherto interest.The system liquid non-solvent used for diluting the film of the composition to be cast, and, as a result, the precipitate-casting resin system, typically by immersion in ORR bath of the nonsolvent liquid system, and may contain preferably contains a substantial proportion of a solvent for the S;,

steme

resinous casting, of

préfërencepïésent

that which is in the solution to be cast.Thus, the system liquid non-self " hill consists of a mixture of a non-solvent the

porosysterue

resinous Å in casting, for example the ADC, and a solvent

pouï

the

gystëme

resinous Å in casting, for example formic acid,

Toutetbis

, in percent, the amount of solvent present in the S,,

stême

nonsolvent liquid will be lower Å in the amount present in it-α-solution casting. Typically, the nonsolvent liquid system will be comprised of a non-solvent, e.g. the ADC, present in amount of from about 40 to 65 degrees; by weight, and a solvent for the system

résineu

-, Angstroms casting, e.g.

lbrmique

acid, present in an amount ranging from about 35 to 60% by weight.Formic acid from the solution Angstroms DAA cast may represent 60 800 angstroms and enjoying the ADC in the electrolytic solution of 0 to 3016 by weight. By expressing these proportions more normally, the formic acid content is from 65 to 75% and the water content of 10 to 20%. Preferably, the bath of the nonsolvent liquid system is maintained at a substantially constant composition in non-solvent and solvent by addition to bath, preferably continuously, the non-solvent in an amount sufficient to compensate for the diffusion of the solvent into the bath from the thin film of the composition to be cast.Solvent forming at least part of the solvent system used in the solutions to be cast may include any solvent for the resin systems to be cast,

c'est

to say the combination of the polyamide resin and the polymer

modifant

, a preferred solvent is formic acid. Among the other useful solvents, aliphatic acids include of other liquids such as acetic acid and propionic acid: phenols as unsubstituted phenol:the cresols and halogenated derivatives thereof " mineral acids

corame

hydrochloric acid, sulfuric or phosphoric acid: the saturated aqueous or alcoholic solutions of soluble salts in the alcohol

corame

ICs chloride

calciare

, the HM!

orure

magnesium and lithium chloride, and ISI hydroxylic solvents, including halogenated alcohols.The only criteria in choosing a solvent tees are the following: l) it is to form a solution of the polyamide resin and the modifier polymer. ¢ 2) it must not react

ehimiquement

neither with the polyamide resin nor with the modifier polymer surface, and ¢ 3) it must be removed

lhcilementpomoir

of the polyamide membrane surface modified. Naturally, practical considerations are also have importance. Thus for example, the mineral acids are pleat dangerous to handle than other solvents mentioned and it must seem to 656,887 corrosion problems. D11 that responds relationto the abovementioned criteria the CT also constitutes a current product, it is the solvent of choice. Because of economy and handling facilities, water is the non-solvent of choice for use in the system Glassware cleaner s when using a non-solvent in the system. DCs analogously, the IC preferred non-solvent for the addition to the solution Angstroms casting thereof is intended to cause the

nucIéation

is water. The non-solvent component and preferred for the system liquid non-solvent used to precipitate the system

résincux

casting from the film of the composition to be cast is also water for the same reasons that the chosen as non-solvent in the solvent system.The membranes prepared have DC they are hydrophilic, skinless, microporous and insoluble in alcohol, with potential flow produced when the fluid flows through the membrane according following

tbrmule

(JT Davis and collaborators,

lnterJåcial

determining amount, when Academic press assembly, York, 1963).(MVs) potential

zëta

=Q-4. Es P in this formula, 1 is the viscosity of the flowing solution, d is its dielectric constant,) is its conductivity, ES is the potential

dëcoulement

and P is the pressure drop through the DCS

mcmbranes

during the time of flow. In 1es following examples, the

quantitéest

kept constant at a value of X 10 - 2 or 2,052, after conversion into

kgim2

, the constant is to be multiplied by narrow distributions of pore sizes, the efficacies of fil15 703.1 conversion factor, so that the potential

zëta

can Bonner ranging from molecular size pyrogens)

jusquä

particles of larger dimension than the diameter of swine,

dimensious

of pores of about 0.04 to 10 micron, with a preferred range of 0, [to 5 micron, film thicknesses in the range of 0.01 to 1.5 mm, preferably 0.8 mm to 0,025, and they have a potential positive

zëta

in a pH range of from about 3 to extended the pores may extend substantially

unilbrmément

from one surface to the other both by size as by the shape, but they may also be wider on one surface than on the

autrc

and, therefore, tapered between the surfaces. Further, the

merobranes

may be characterized in that they have surface properties can be substantially influenced by the cationic quaternary ammonium groups of the cationic surface-modifying polymer, quaternary ammonium, thermoset. Surprisingly, the small proportions of the quaternary ammonium polymer surface modifier added lead to membranes having surface features that reflect

pratiqucment

the presence of the cationic quaternary ammonium groups. With their excellent porous structure and their positive zeta potential, these membranes contain very low amounts of extractables, which makes them especially advantageous in pharmaceutical and electronic filtration applications. Further, the membranes may be prepared conveniently and economically by a continuous process directly as described hereinafter.The membranes surface-modified with low or moderate amounts of polymer modifiers, subjected Å the resistivity test described below, require rinsing times of 10 minutes or less, preferably less than 5 minutes for delivering an outgoing water to a resistivity of

mégohmsícm

14.It is believed that the surface-modified membranes, particularly those containing polymeric surface modifiers in quantities small or moderate, DCs have short periods of flushing due to the apparent interaction between the IC and the surface modifying polymer end groups of the polyamide resin. It is believed that this interaction and the integral nature resulting therefrom for the membranes of the

invcntion

leads to decrease in extractables drivable

transportëes

and then through the filter into the effluent, a phenomenon occurring presumably with the coated solid supportand membrane features.Now will describe the procedures of tests used in the following such as the membranes modified surface.The properties of the membranes, in the examples which follow, have been appreciated by several assay methods which are described below:(has)

Potcntietzëta

the zeta potentials of

mcmbranes

were calculated from the results of measuring the streaming

écouIement

produced by a solution of 0,001% by weight in the ADC kc1 distilled through several layers of the diaphragm secured in a filter fabric or in a membrane support. The potential

zëta

is to measure the load stationary electric net on membrane surface exposed Å in a fluid. 11 is related to the Give expressed by the formula:Zeta potential (MVs)- 14.43 Associates (

voltsl

L (

gmhoicm

) P-

kg

/cm. - ') to EB) ability of the membrane to the

absoiTtion

a

tatex

is

piace

a disk membrane 47 mm diameter in a filter holder with a filter surface of 9.29 cm2 and then subjected to test with a suspension of 0.01% by weight of monodispersed latex spheres in an aqueous solution at 0.1% by weight of Triton-X 100 (an adduct of about 10 moles of ethylene oxide with nonylphenol, commercial good. The suspension of latex is

pompëe

through the membrane

Faide

angstroms of a syringe pump model where commercial midwife implement 341 2 mi/min rate. The effluent of the latex is detected by the diffraction to 90 of 537 nm, measured in a photometer to

Faidediffiaction

light

Brice

-to-Phoenics LP 2000 with flow cell.The solution of latex is pumped through the membrane until the diffraction of light by the effluent begins to defer DCs that observed for a solution of 0.1% Triton-X 100 alone, which indicates the beginning of the year

pénëtration

latex particles through the membrane. The absorption capacity of the latex (lake) is calculated by the following equation:10xv lake (mgs!

cmz

929.0 where V is the number of ml of latex suspension to 0.01% by weight which was able to pass through the membrane until the shift is occurring latex.(d) reducing the bacterial count is placed to the autoclave sterilized membranes in filter media suitable stainless steel and exposing the filter holder with the

membranc

in

piace

to water vapor to 123 30 min followed by C. for a period of 60 minutes in

dëv

exhausting a sterilizer laboratory

Vernitron

/model where the Better-to-

BuiIt

XX 21 222. The OH then submits to tests with bacteria to 4 levels: 10õ, 108, the O l0, 10, 2 bacteria per megahertz for a total amount of about l0 Z-b-Regional Exchange Topic fixable by Mz of diaphragm (this is the Bacteria Limited

Titer

reducing test of the United States Pharmacopeia).Effluent is collected under aseptic conditions in a sterile glass container. Determination of the number of affluent

baetéries

in O and to the effluent by forming serial dilutions of these suspensions and depositing them on a 0.22 micron in the analytical membrane. These membranes are cultured on agar

MullerHinton

C. for 24 hours to 38 for colony growth of

Serrathtmareeseens

and during 48 hours for the growth of Pseudomonas

diminttta

co6s

lonies

.Then colonies are counted

eroissant

on!in ES cultured membrane and it can be assumed that the number of colonies observed is equivalent to the number of bacteria in the deposited solution.656,887 as in the case of reducing the adsorption as latex particles, TR is defined as the ratio of the bacterial count bacterial count at influent waste:T-account=account influent waste (D.) one

opératoh

' th test "Te-dt-reduction" exemplary

endotoxVw

wagering is wetted beforehand a 47 mm diameter disk I membrane subjected to testing by isopropyl alcohol and is

piace

l0 d-ns to a disk medium of 47 mm

dépyrogëné

a filtering surface of the Mz 0.000929 previously depyrogened by heating in an incubator at 250 C. for 1 hr. Is passed through the membrane under test 50 LTA of ADC pyrogen free and is collected from the LOS last 3 to 4 LTA in glass apyrogenic: is the LOS retains as ls cookie for the system, then sent to membrane aliquots of 10 successive LTA purified endotoxin e. coli 055: b5 at rate of 5 mi: 8929

cmz

/min, and the effluent is collected it is preserved as above. The first aliquot is at a concentration of 1 nanograms/ml.: each of successive portions is at a z0 concentration of L 0 times the concentration of the previous one, up to a maximum of 100 mg, per ml. Diluted!in ES solution inflowing and effluent by the ADC apyrogenic in necessary quantities and screened Å the analysis the presence of endotoxin by testing "

AmebocyteLysate

Limulus anti-testing" (United States Pharmacopeia redundantable, 1980, page from 2s 888).(i)Q-resistivity of the ADC (]

htente

prior preparation is microporous membranes

hydrophileì

polyamide-modified surface as standard

cartouehes

by conventional techniques, forming cartridges having a filtering surface of 0.70 mi. Is then scanned across the LOS cartridges by!' 0, 2m ammonium hydroxide with a pressure of 3.5 kg: cm2 on the cartridge during 6 minutes to passing the surface modifying polymer in the hydroxide form. Is then scanned across the LOS cartridges by 1.5 1 of demineralized water to

dëliminer

ammonium hydroxide residual is then dried for 12 H at 79.4 C. the cartridges are then ready to testing aimed at greatly accelerated

idence

Angstroms their ability to provide ADC effluent to high purity test procedure the resistivity.Testing of £Res

çtivité

is produced ADC to a resistivity near net theoretical value by passing of the ADC city on a bed demineralizing commercial model where my 18090-dealer Inc. in evenings, then on two beds 4s commercial ion exchangers

UnibedCulligan

Inc.-dealer. The LOS membrane is mounted under test as

cartouehes

standards in a cartridge housing construction is subjected to a usual and flowing about!0.8 1 by m2 of membrane surface and per minute using the DAC which originates from the demineralization system. The water from the elements is constantly monitored for its resistivity using a conductivity cell model where commercial 3418-dealer Chromophthal BSH implement Company analysis. The conductivity cell is connected to a bridge-dealer model where conductivity 31 Chromophthal BSH implement SSs Company la allows direct measurement of the resistivity of!' effluent from the duration of flow of water. Determining the time in minutes required to reach a resistivity of the effluent 14 megohms per cm, the limit of water quality generally accepted by the electronics industry.One

opératoõ

' th general I for preparing Tc-casting

contitl

membranes examples I to 12 below:Is dissolved resin pellets of nylon 66 in!' to 98.5% formic acid. The resin is added commercial already mentioned in a resin

r43õ8

sufficiently activated, 5% by weight solution in the ADC 6s, in sufficient quantity to carry to the desired value the relative proportion between the resin and nylon 66. r4308 solution casting made of homogeneous (1) casting the resin system,

c'est

fi e. nylon 66 and the

rësineR4308

, and (2) the system solvent,

c'est

to say

lbrmique

acid and the ADC, is subjected to viscosity measurement at 30 c to the

apparcilRionViscotester

model where vt04-dealer of EXTECH International TX, terrier, on mass ., United States, with rotor rotating at no. 1 63.8 towers, min, found a viscosity of about 6000 centipoise. After the viscosity measurement, supplying the casting dope

Faide

to a metering pump, at flow rates ranging from 250 to about 1500

gmin

snout in a mixer in series of conventional design to 6.35 cm rotor whose!' mixing intensity is

contrõlée

speed interval in a wide area. Simultaneously, a non-solvent is added, of the ADC, as indicated in each example, injection metered into the mixer, as needed to achieve the required water/formic acid ratio and cause nucleation of the solution to be cast and obtain a visible precipitate.The output of the mixer, the casting composition is filtered through a 10 micron filter that removes the LOS resin particles visible, and then cast onto a continuous piece moving polyester porous fibrous, nonwoven, 27.30 cm in width, to]' using a scraper blade at spacing of about 0.0203 cm. Within a time less than 3 seconds, the fabric is dipped in a

revëtue

membrane formation in the system

consistaut

nonsolvent liquid,

c'est

say a mixture of formic acid and water whose composition is given in each example, during 3 minutes approximately 1 Angstroms. The concentration of the bath is kept constant by continuous addition of water by an amount for compensating the diffusion of the solvent into the bath from DC film DC casting composition.The nylon membrane thus formed on the porous carrier fleece polyester is

laxée

to water for about 3 to 6 min

añn

eliminate residual formic acid. Excess moisture is a nylon membrane

éliminë

DCs through shifting of the L MES-fitting room in tension rubber layer and the membrane is in the form of desired size

rouleanx

for preserving or Los subsequent treatments. For application in filtration or!aE tests of the nylon membrane to the state of the quail planar, the membrane sheet is mounted in a frame which

retenneempëche

retraction in all directions and the LOS are dried the membrane in an incubator at 143.3 C for 5 minutes. The membranes are then in the form of filtering

cartouehes

by known techniques and under test is the lead application in filtration processes in the form of cartridges.The examples which follow illustrate

lïnvention

without however limiting its scope; in these examples, the LOS indications parts and percentages by weight except mentions extend counter.

Exemph

, 1:By using the method of continuous casting described under the title "general procedure I-" above, for preparing a polyamide membrane microporous hydrophilic surface modified. The casting dope is prepared by mixing about 549 parts formic acid, 92.2 commercially available parts of the resin in a resin r4308 activated, to 5 degrees, '

ó

in water, and 108.1 parts of resin pellets of nylon 66. the mixture is subjected to mechanical agitation

jusquä

homogeneity.The casting dope is pumped into a mixer rotating at 3600 revolutions in series: min at flow rate of 1000 g per minute; at the same time supplies, is injected 1" water to the mixer at rate of 36.4

gímin

. The casting composition thus obtained is then

passëe

through a filter of l0 microns which removes visible particles.The casting composition is maintained at temperature of 48.5

uue

: c and cast on the polyester fabric to!' using a scraper blade at spacing of about 0,020 cm. The fabric passes the scraper blade at a rate of about 15.2 m-min and then passes the d ns in a bath containing 50.1% formic acid, balance: water. The membrane is then processed as discussed in the

opëratoire

I above,

c'est

to say that it is washed and then

sèchée

in a retention frame during minutes at 140 c and is now ready for applications in filtration or tests.

E.vempl

" 2:This repeats of the example I, but the solution to be cast is made of approximately 374.5 parts formic acid, 53.0 parts of an activated solution to 5.82% of the resin molding material r4308 in water and 72.5 parts resin nylon 66. the casting dope is pumped at rate of 500 grams/min through a series mixer rotating at 2718 revolutions/kidney; in

meine

time, water is injected into the mixer at 24.9 grams/min. flow rate. The casting composition thus obtained is kept 54, 0c and cast on the polyester fabric traveling at!0.1 meters/minute.

Lëtoffe

is then immersed in a bath

contelnaht

0 45% 55% of formic acid and water and then treated as described above until it is available for Ou filtration applications or tests.Example 3: I-

rëpète

operation is described in example 2, but the speed of rotation of the mixer in series is 2717 turns!min and water is injected into the mixer at 17.9 grams/min. flow rate. The temperature of the casting composition is maintained at 54.7 C. fabric

revètue

passes in a bath containing 55.4% formic acid, balance: water, at a speed of m/min. z0 10.1. The membrane is then treated

commc

described above until it is ready for applications in filtration or tests.Example 4:Prepared as described above a solution casting consisting of about 73.2% formic acid, 12.3% water, 14.02% nylon 66 and 0.43% of the resin molding material r4308 activated. The casting dope is pumped into the mixer in series rotating at 3600

toursimin

at 1000 grams/min. flow rate. In the mixer, is injected in the CSU

mëme

time rate of 32.9 grams!min and composition is kept casting at a temperature of 47, 6c. The polyester fabric to the passing

raeleuse

0.01 cm spacing at the rate of 16.8 meters!and then into the bath containing

miri

50.1% formic acid, balance: water. The membrane is then processed as described above until it is ready for applications in filtration or tests.Example 5:Repeating the process of forming the membrane of the example 4, but the proportion is adjusted to 2% of a resin r4308 compared to nylon 66,

c'est

to say that two parts of the resin 100 parts r4308 for nylon 66. the casting dope is fed to the mixer at 1000 grams/

miri

flow rate and the temperature of the casting composition formed under these conditions is maintained at 47.5: C..The fabric traveling at 16.8 meters/min is immersed in a bath containing 49.6% formic acid, balance: water. The membrane is then processed as described above until it either

prëte

for assay or filtering applications.Example 6:Repeating the process of forming the membrane of the example 4, but the proportion is adjusted to 1.5% of a resin r4308 compared to nylon 66,

c'est

to say that 1.5 part r4308 100 parts resin molding material for nylon 66. of the CSU is introduced into the mixer in series at rate of 28.7 grams/min and the temperature of the casting composition is maintained at 47.1 - C. the fabric traveling at the speed of 18.3 meters/min is immersed in a bath containing formic

acidc

of 50.1%, balance: water. The membrane is then processed as described above until it is ready for applications in filtration or tests.Example 7:Repeating the process for the preparation of the membrane of example 4, but will adjust the ratio of the resin molding material to nylon 66 to 1.25% r4308 in the solution casting,

c'est

to say that 1.25 part i00 r4308 resin molding material for nylon parts 66. water is introduced into the mixer at rate of 28.7 grams/min and the temperature of the casting composition 656,887 48.0 is maintained:: C

Lëtoffe

traveling at the speed of 16.5 meters/min is immersed in a bath containing 50.2% formic acid, balance: water, and then further processed as described above until ready for assay or filtering applications.Example 8:This repeats of the example 1, but used a casting dope that consists of about 487 parts formic acid, 58.9 portions of an activated solution to 2% of a resin r4308 in water, 9.9 parts water and 94.0 parts resin nylon 66. the casting dope is pumped at rate of 500 grams/min through a series mixer rotating at revolutions/min. 2648; in

mêmctcmps

, in the mixer is injected water at 25.3 grams/min. flow rate. The casting composition thus obtained is kept 53.7 c and cast on the polyester fabric traveling at the speed of the m/min at 10.4.

Lëtoffe

is then immersed in a bath containing 54% formic acid, balance: water, and processed as previously described until ready for assay or filtering applications.

Ævemph

, 9:This repeats of the example 8, but the rotation speed of the

mëlangeur

in series is of 2631 turns/kidney and water is injected into the mixer at 12.0 grams/min. flow rate. The casting composition is maintained at 55.9 c before poured onto 1" polyester fabric traveling at the speed of the m/min at 9.1. The fabric is then immersed in a bath containing 54% formic acid, balance: water, and processed as discussed

préeëdemment

up to EE it ready for the filtration applications or CSF assays.

E.v

"

llçl

" 10:This repeats of the example 8, but the rotation speed of the methods for the:

mgeur

in series is 2719 turns!min and water is injected into the mixer at 4.4 grams/min. flow rate. The casting composition obtained is kept 58.7 c and

coulëe

on the polyester fabric traveling at the speed of 6.7'm mins.

Lëtoffe

is immersed in a bath containing 54% formic acid, balance: water, and processed as previously described until it is ready for application in the filtration tests.Example 1! :This repeats of the

exelnple

8, but the speed of rotation of the mixer in series is 2651 revolutions/min and water is injected into the mixer at 6.5 grams/min. flow rate. The casting composition obtained is kept 57.4 c and cast on the polyester fabric is

dépla4sçant

at the rate of 7.9 meters/minute. The fabric is immersed in a bath containing 59% formic acid, balance: water, then

traitëejusquä

as previously described that it is

prëte

for applications in filtration or tests.Example 12:This repeats of the example 2, but the speed of the mixer in series is 2719 revolutions/kidney and water is injected into the mixer at 7.5 gm/min. flow rate. The casting composition is maintained at a temperature of 57.3 c and cast on the polyester fabric traveling at 6.7 meters! minutes. The fabric is in a bath containing 55%

immergëe

formic acid, balance: water, and processed as previously described until it is ready for the applications in filtration or testing.The

diamëtres

pore membranes examples! to 12 and the comparative membrane prepared from nylon 66 without the addition of a modifying polymer surface of the membrane were determined by measurement of KL as described in United States Patent the n " 4,340 479 above: the results are reported in table I below. The K, denotes the pressure at which the flow rate of air through the membrane 6s wet by water increases suddenly. It has further been determined the zeta potentials and adsorptive capacities membranes by the procedures of assays) and b)

respectivementles

results are also reported in Table I.656,887 table membrane of the resin molding material of the comparative example 1, 2 3, 4 6, 7 8, 9 11, 12 Bo is r4308 added relative Å in the nylon resin 66, 4.1 4.2 4,i 3.0 2.0 1.5 1.25 1.25 1.25 1.25 1.25 4.2 nothing pore diameter calculated (micron) 0.1 0.2 0.45 0.1 0.1 0.1 0.1 0.2 0.8 3, 1.2 1.2 0.1 zeta potential at pH 7.5 + 15 + 22 + 19 + 13 + 13 + 12 + 13 + ll + lg + 12 + 16 + 25 - 20/

CmillivoltsCapaeité

adsorption for a latex of O, 03g microns milligrams per m -) 1033, 1141 936,743 936,377 560,226 312, 86 248,452 0 the results reported in table I above show that the inventive method for preparing surface-modified microporous hydrophilic membranes gives membranes which have potentials

zëta

positive in alkaline pH. Further, they show that this method can be prepared by cytopathy membranes having pore diameters of from very different. In addition, [AE adsorption capacities indicated Los latex spheres 0,038 microns,

c'est

fi e. particles whose diameter is less than the

trës

pore size (pore

diamo.tre

) of these membranes, the effectiveness of these membranes increased for extremely deleterious to particles, as compared to well the comparative membrane, a microporous membrane hydrophilic nylon 66 prepared by the method of Patent U.S.

Amériqne

no. 4,340 479 above. By

eonséquent

, the membranes are superior to the membranes not

modiñëes

U-in filtration applications [

trafine

.It has also subjected the

mero

.in the example 12 to

brano

tests of ability it-removal of the bacterium e "

rratia

Mars"

escens

of an aqueous suspension by the test method of reducing the bacterial count Cl described above. By contrast, was also subjected to the ": an identical membrane but tests made without addition of the modifier polymer on [: CEA: the LOS results obtained with this membrane are also reported in the table the Li

cí

-on-, sounds the mention" benchmarking ".

Btbå

, to the H-b '

ffïcacité

SEEN on' the ATIA

marcesc

"nsec membrane of microorganisms used reducing the example by Mz of membrane surface as the comparative x 12 10iz 5.5 10" 5.5 x reported results in the table above demonstrate the greatly increased efficiency of about i00 000 times)

dëlimination

bacteria Los filter membranes prepared PREA addition of a modifying polymer, comparatively Angstroms membrane like the comparative non-surface modified.The membrane has been subjected!' example 3 testing of removability of e. coli endotoxin contained in an aqueous suspension by the test method of reducing endotoxin as described above sounds of d). It is believed that this endotoxin is to dimensions

molécalaires

and exists as

båtonnets

about 0,001 micron in diameter. By contrast, were tested simultaneously with a membrane like ("comparison") 0 prepared without modifying polymer surface of the membrane; the results obtained are reported in Table III.Table III diaphragm concentration of the endotoxin E. OE/I into the example nanograms per LTA, necessary for effluent 3, 1 o0 000 positive comparison 1 unexpectedly, the membranes of the invention provide extremely important in

amêlior

ing

díélimination

efficiency compared to bacterial endotoxins

modiñées

non-membranes. The

présenee

a small proportion of modifying polymer membrane surface leads to a multiplication of about 10õ 000 times of

Fefiícacité

for removing endotoxins from by the membrane.It has been surprisingly shown that the PREA

lïnvention

membranes according.which are heading bdenoting

dëliminer

undesirable materials possessing biological activity, are also capable of decreasing an adsorptive removal of certain desirable

eomposants

filterable of pharmaceutical compositions. Thus for example,

préparëes

membranes has been effected in the process of example 2 tests the DC filtering a solution of benzalkonium chloride, a preservative commonly used in [AE pharmaceuticals, unacceptable without decreasing the concentration of said substance. Which was passed through an aqueous solution to 0.04 degrees " DCs benzalconium chloride in two layers of 47 mm diameter disks 11, 656887 rate of 0.71 per minute 929 cm2 and determined the concentration of the preservative in the effluent relative to the concentration in the influent

tbnetion

the volume delivered. By contrast, were subjected to tests like a nylon membrane 66 of commerce to the

mëme

pore size ("comparison").gHG results obtained are reported in table IV.Table VI diaphragm size production (929 for

IRrescmz

) required to achieve a pore % indicated of the example (micron) concentration of the influent 90% 95% 2, 0.2 1.5 3.2

ComparativeI

0.2 4 reported results in table IV above show that the effluent filter membranes reaches acceptable concentrations significantly Ini the effluent of the membrane the comparative. It is a great advantage when filter such pharmaceutical compositions because there is less loss of the amount of

eonservateur

necessary.Procedure g at the Li

zéral

&: preparation by a batchwise operation "tees membrane" examples 13 and 14 in the LOS the LOS examples that follow, are prepared

mémbranes

polyamide containing surface modifying polymers of different types by the batchwise operation follow: solutions prepared by dissolving resin casting resin pellets of nylon 66, the same resin as in the examples 1 to 12 naked! other polyamides indicated in the LOS examples) in a solution of formic acid and the modifier polymer surface indicated, the dissolution is carried out under stirring to about 500 revolutions:

rëacteur

reins of minute in a double shell maintained at 30 C..When the dissolution is complete (usually after 3 hr), is added to the solution to a non-solvent, water, in sufficient quantity to adjust the final concentration materials at the levels indicated in each example. Water is pumped at a rate of about 2 ml ., minutes through an orifice diameter of about 1 mm below the surface of the solution to a point spaced approximately 1 ROS of the stirring blade. The agitation is maintained at about 500 revolutions/minute during the addition of water to induce nucleation, the casting composition is filtered through a filter of microns; about 40 is then

étle

g of the composition to flow obtained on a clean ice using a scraper blade with adjustable space. The film is then immersed rapidly in a β in-containing formic acid and water to the proportions indicated in the examples that follow.The membranes are kept immersed in the bath for several minutes and then are peeled from the ice. Are washed in water to remove residual formic acid and dried

lëtuve

during 15 minutes to 96: c to the retained state in a frame so as to prevent retraction. The sheets of planar

memtbranes

are then used for applications in filtration or for tests.The a temple 13:A membrane is prepared by the general procedure II-above with a modifying polymer surface which consists of the polymer commercial

Polycup

1884, a polyamidoamine resin!polyamino epichlorohydrin described above having a density and a viscosity of 1.12 325

cenUpoises

in aqueous solution at 35%.The casting dope contains about 74.2% formic acid, water 10.0%, 14.3% nylon 66 and 1.43% of the resin

Polyeup

] 884. The casting composition is spread film into the windshield

dëpaisseur

0,038 cm and immersed in a b-in-containing 54°ó formic acid, balance: water. The membrane is then treated as

dècrit

above

gènéral

II is in operation mode.The resulting membrane is wetted instantly upon contact with water (less than one second) and has a pore size of 1 micrometer

envìron

, as

dëterminée

by measurement of KL. Found for the membrane a zeta potential at pH 8.0 de + 2.8 MVs.Example 14:ls a membrane prepared by the general procedure it resin such as polyamide poly - (hexamethylene

azélaroide

) (6.9 of nylon) and as the surface-modifying polymer resin molding material r4308 activated. The casting dope contains about 65.4% formic acid, 17.7% water, 16.0% and 0.8% of nylon 6.9 r4308 resin molding material. The casting composition is spread film DCs

dëpaisseur

0,053 cm on a ice and then immersed in a bath containing 60% formic acid and 40% water. The membrane is then processed as described above in the

opëratoire

generally Li.The membrane of the example 14 is completely wetted year immediate contact with water (less than one second), it has a pore size of 8 microns as determined by measurement of KL, it has a zeta potential at pH 8.0 MVs de + 3 and thus, the membrane

prëparée

by this method is microporous, hydrophilic, and perceives a zeta potential

pré3upositiîen

alkaline pH.We

ufilisé

the continuous operating method in preparing the membranes (procedure

génërai

I above) for preparing a plurality of diaphragms each having a pore size of 0.1 micron and containing varying proportions of resin molding material r4308 added. The preparation of these membranes is described in the LOS examples 1, 4, 5, 6 and 7. the

membrancs

knockout been prepared under identical conditions from solutions comprising casting the resin molding material in an amount of about 4% r4308 falling up to about 1%. It has also prepared a membrane like, but without the resin molding material r4308 by the method Patent of the United States of America mentioned no. 4,340 479; franchise is of a comparative example and the membrane is called "benchmarking" hereinafter.These membranes are subjected to tests for determining the zeta potential at pH 7.5 4s. All membranes prepared by adding the resin in a resin r4308 (of 1.25 to 4.1% by weight) have a zeta potential strongly positive. The membrane of comparative, prepared without the resin in a resin

R4308

, has a strongly negative zeta potential measurement under the same conditions. As a result, even small additions of resin molding material of r4308 give membranes having a zeta potential strongly positive and an improved filtration

efñcacitélëgard

to negatively charged particles in aqueous suspension.It has also transformed the membranes of examples 1, 4, 5, 6 and 7 in filter cartridges by known techniques. It has scanned these filter cartridges with ammonium hydroxide o,2m with a pressure of 3.52 kg/

cmz

Los cartridges during 6 minutes was then scanned by 1.5 liter of deionized water. Was then dried for 12 hours at 79.4 C. has submitted the filter cartridges of assays for their ability to deliver, g0 rapidly after the start of the filtration, water outgoing high purity and ultra ion, according to the requirements asked for filtration of an electronic grade water. By contrast, was used in the same test a filter cartridge containing the membrane of comparative, prepared under analogous conditions but without the modifier polymer surface; the results obtained with this cartridge include under the mention "comparison" in table V also included in this Table V times necessary for the effluents of these filter cartridges 656,887 12 reach a resistivity of megohms i4, the measurement being made

tielszëta

and] AE capabilities particle absorption membranes as described in the testing of resistivity above, as well as the

potenfiltranteTah

[

eatt

V-membrane such as I the comparison 4, 6 7% resin r4308 added to the nylon resin 66, 4.1 3.0 2.0 1.5 1.25 nothing potential

zëta

(millivolt) PTT 7 adsorption capacity of latex spheres 0,038 + 15 + 13 + 13 + 12 + 13 - 20 microns (mg;m2) duration (minutes) at 1033.34 742.71 936.46 376.73 559.72 0.0 at the end of which the effluent reaches a resistivity of 14

mégohmsicm

22, 7.5 2.0 2.5 2.5 reported results in the table show that the membranes have new properties for use in the filtration of water electronic, compared to the membranes of the prior technique. The membranes surface-modified according to the invention have positive zeta potentials in alkaline medium, separation efficiencies significantly improved in respect of the P

rtieu¿

ultrafine powder is the capability of delivering a purified effluent ultra ion rapidly after ISI beginnings of filtration.Single Figure of the attached drawing represents graphically the relationship between (1) the amount of time that passes after the start of the filter before the filtered water has the resistivity required 14 megohms; centimeters (this is the rinsing time reported question in the resistivity test described above), and (2) the percentage of resin molding material r4308 added: has been reported on the graph the flushing time depending on the % of resin molding material r4308 added for each of the filter cartridges above. This graph shows that the rinsing time decreases in linear function when the quantities of resin molding material r4308 added decrease. The results of R

ppùrtés

in table V above show that, to an addition of about 1 to 1.5% of a resin r4308 added, the resulting membrane has a zeta potential strongly positive and a rinsing time practically identical to that of an unmodified membrane. This behavior is

extrëmement

advantageous because the membrane effectively provides high water resistivity and yet retains the improved efficiency of filtration by electrostatic effects.Example 15:Subjecting a hydrophilic microporous membrane surface modified polyamide, prepared by the process according to the invention from nylon 66 used in the examples 1 to 12 and the resin in a resin

R4308

, to a pore size of 2 microns thick, tests OS where it is desired to highlight the ability of separating particles causing the disorder and the precursors of disorder of a commercially available alcohol (cherry brandy) to 40% alcohol by volume.Before filtration, is cooled alcohol OC about: at this temperature, it is much disorder, thereby indicating the presence of an insoluble phase dispersed, finely divided state. Passed]' alcohol cooled through a filter media comprised of two layers of]

microporense

membrane described above. To this end, there is mounted a disk 44 mm diameter made of two layers of DC membrane described above in a membrane support and is passed through the alcohol refrigerated filter medium at a flow rate of 0.5 ml, ; min for 929 cm: membrane surface.The initial pressure drop through the filter media is 0.32

kgícmz

. After 5 hours of operation, the pressure drop mounted to 0.51 kg!mHC during 5 hours filtration, the effluent guard a light and crystalline, free of any ladle. The total volume of alcohol filtered in the period of 5 hours corresponds to 125 liters for 929

cmz

filter area. After filtration, the alcohol is permitted to return to ambient temperature. It is not cloud, even when le refrigerates again, alcohol remains clear.This example shows that a membrane according

lïnvention

can be used for the treatment of alcoholic beverage you want to clarify and protect against the formation of haze.Example 16:To carry still demonstrate the ability of the membranes of the present invention to operate correctly in some filtration applications suchre uests that the preparation of water-resistivity adjacent I theoretical resistivity of its production electronic, undergoes a series of elements a to d

dëcrits

hereinafter tests for determining "

extraetibles

materials" by the procedure also described below.In this test series, corrugated filter elements are prepared conventionally designed to

surìace

useful about 0.46 m2 by conventional techniques be constructed three membranes

microporeuscs

different. These elements, designated a to d in the table VI hereinafter, have been

prèparës

Angstroms membranes that were themselves prepared as described below.Elements A it is a polyamide microporous hydrophilic membrane to a pore size of 0.2 microns that was prepared by the general procedure described in the Patent of the United States of America no. 4340479 from nylon 66 used in] AE examples I to i2 of this patent. On the membrane formed, the resin molding material is coated r4308 by impregnation with a solution of 3% r4308 in water; the resin r4308 has been activated beforehand in accordance with the manufacturer's recommendations; after impregnation, was wiped off the membrane to remove excess resin is then

transformë

the membrane in the filter element called a in the table VI below.B. the membrane element b was prepared by the same method as the membrane element A. She also has a pore size of 0.2 microns.C. the membrane prepared by the method of casting in common according to the invention from (1) nylon 66 already used for the membranes of elements a and b above and (2) the resin r4308. The resulting membrane also has a pore size of 0.2 micron and is made up of 98% and 2% of polyamide

R.esin

r4308.D. (comparative,) this membrane comparison was prepared by the method described in the Patent of the United States of America no. 4,340 479 from nylon 66 identical to those of the a and b above. The resulting membrane also has a pore size of 0.2 microns. It does not contain a modifying polymer (1) nor T-s an integral structure unlike element c) nor (2) as a component of coating of the membrane (unlike elements has and bi.The filter elements a to d described above were subjected to the following tests:A TES has been effected elements a and b separately to an extraction step by passing on these elements, the duration indicated in the table VI hereinafter, 1.8962 liter per min and by water element

démiaéralisée

at room temperature. This

o0ération

extraction was performed to eliminate to the greatest possible amount of soluble matter elements a and b. nor the element c nor the element d were not subjected to this treatment.After the extraction operation to water carried out on the elements a and b, OH subjected each of elements separately to one scan to the ADC demineralized at room temperature under the pressure and the duration indicated in the table VI below. It should be noted that the times and pressures scanning have lead to a total water

eourant

13,656 887, pure each individual element, of about 189 liters for the elements a and b and 227 liters for the elements c and d.After scanning to deionized water, were filtered elements to C. for 12 hours 96° and was treated to the steam at 121 °C. for lots Delhi Angstroms I-hour was then re-extracted each element separately by the ADC demineralized. The extraction operation was carried out by closing the foot of each element and placing each element in a separate bath of 1.5 liter of deionized water and then returning each of the antiparallel (the

sommct

of the filter element exceeds about 5 cm the higher level of the bath in the initial position), during 4 hours.In each case, was then evaporated bathing water is weighed and the non-volatile residue to determine the extractables of each filter element. The results obtained are reported in the table VI ls El-after.Table VI materials (mgs) extractable element 96 AB C. D.

Extraetion

by the ADC demineralized minutes minutes nothing nothing sweep DHoU demineralized min to 1.4 bars min to 1.4 bars 3 min to 3.5 bar 3 min to 3.5 bar 68, 27 zeta potential (by TUV) 18 - 20 18 - 20 18 - 20 -18 reported results in the ' table VI show that in a TES elements c and d, the quantities of substance

extraetibles

markedly reduced

eomparativement

elements prepared with polyamide membranes coated (a and b), this although the elements a and b have been extracted to the demineralized water (30 and 60 minutes respectively). It is also possible to ascertain the investigation results reported in the table VI that element c, prepared by the process of casting in common according to the invention, contains less extractables that the comparative D however, element c combines the advantage of the zeta potential at pH 7

positifà

(and higher pH) with that of the low extractables

extraetibles

comparative element d which rather a negative zeta

potenticl

7 pH (pH's and higher), inconvenient for many applications.Usability

Uldustrielles

shown a TES surface-modified membranes according to the invention were higher by many properties important in filtration membranes prior untreated.They are also superior to

nombreûx

respects to the coated membranes, for example by the increased efficiency in the use of the surface-modifying polymer and in surface properties of the end products comparative. They can be used in filtration applications as they are manufactured, with or without the incorporation of the mounting bracket. One may combine or provide between them two, or more, membrane filter sheets to form multilayer membranes or tees into filter elements by known techniques and for use in a TES

eartouehes

filter, such as filter elements in the form of corrugated sheets supported within a cartridge of conventional type.The membranes exhibit positive zeta potentials in a pH range of from about 3 to extended 10

eonsidérablement

separation and efficiencies are improved with respect to negatively charged particles in aqueous suspension. Further, they knockout improved efficiencies in separating bacteria and endotoxins contained in aqueous fluids. In addition, the physical properties and chemical properties to their capability to provide

eouplées

rapide4s telling a high purity water free of ionic impurities

micropartieules

and render these membranes are particularly advantageous to use in making

mieroélcetroniques

.The membranes find use in the

industrìe

and in the medical field for the treatment of water for critical applications as the ADC for injections medicinal, the manufactures microelectronic for the reasons set forth above, the filtration of the blood serum contributing to infertility, the parenteral fluid filtration and generally any use wherein an ion-containing liquid to be filtered with a high SSs degree of clarity.The R 1 sheet drawing OPO o0/1 fig. sheet. I - p-O - O-ER 4 b° %. the m 3 IDs gm, I-I-I-I-shall Õ - i0 15 time needed to reach 14 megohms, min.