Method of composite layer's pores porosity and mean size control

A controlled pore-sized composite poly-terafluoroethyl product and a process for its production of a vehicle with a controlled pore size and a pore size.

Field of technology

The present invention relates to articles having a composite structure and to a process for their manufacture, said articles comprising a polytetrafluoroethylene fibril matrix (PTFE) with controlled pore size and void volume, these composite structures being suitable as selective sorption or reactive media for separation applications. , diagnostics, extractions in the field of environment, clinical extractions, catalysis, special layers and the like.

Prior art

The field of separation and purification is well known in science, and two journals, namely Separation, are mainly devoted to this field

Science and T_6Chnology a Separation and Furifikation *

Me'thods. Both are published by Marceli Dekker, NY, · NY. A number of book publications on the subject are also known in the art. Finally, any practical chemist needs one or more reliable separation and / or purification methods, including scrubbing techniques. These techniques are mediated by compositions comprising a sorption medium for separating (i.e., separating and analyzing) the mixture by selective sorption and desorption of components in the mixture.

Sorption media in a polytetrafluoroethylene (PTFE) matrix have been described in the field of separation.

U.S. Patent No. 4,810,381 and related Patent Nos. 4,908,378 and 4,971,738 disclose a composite chromatographic material comprising a polytetrafluoroethylene fibril matrix

-2a non-swellable particles introduced into the matrix.

U.S. Patent No. 4,153,661 discloses a method of making a polytetrafluoroethylene composite layer comprising a PTFE matrix with a. Essentially a water-insoluble particulate material dispersed therein. The resulting layer is extremely flexible, similar to goatskin. It is said to be suitable as an electrical insulator or a semipermeable membrane.

U.S. Pat. No. 4,373,519 discloses a composite medical dressing which has been used in a plurality of forms. water-swellable particles introduced into the matrix and optionally a partially occlusive film covering one surface of the matrix. These layers are said to be conformable and suede-like.

U.S. Patent Nos. 4,565,663 and 4,460,642 in connection with U.S. Patent No. 4,373,519 (part of the continuation of the application and continuation of the application) disclose water-swellable composite layers having a PTFE matrix that can be water-swellable hydrophilic absorbent particles' ^xThese layers are described as adaptable and similar to velvet. Certain water-swellable cation exchange resins in composite layers can be used as chromatographic materials.

U.S. Patent Nos. 4,722,658 and 4,761,771 disclose composite articles comprising a polytetrafluoroethylene fibril matrix into which living organisms, bacteria, fungi or yeast cells are introduced.

Several formulations for mixing an aqueous PTFE dispersion with various additives and / or auxiliaries designed for specific purposes are also known in the art. It is also stated in the art that these particles or additives with an aqueous PTFE dispersion

-3 forms a mass having a gypsum or pasty consistency and only a specific addition of a sufficient amount of lubricant exceeding the sorption capacity of the particles (see e.g.

U.S. Patent No. 4,810,381, column 6, lines 22-30j, see also U.S. Pat. No. 4-3-735-1-9, 44-6-0.64.2_a-45656.63-X._Nav-íc —US-pa ^ -_:---— This No. 4810361 specifies the procedure for exceeding the sorption capacity- (see column 6, lines 25-33).

U.S. Patent Nos. 3407096, 3407249 and 3556161 disclose the incorporation of extractable or leachable organic filler particles at different levels and different sizes into composite layers providing the desired porosity for their applications. U.S. Patent Nos. 3864124, 4194040, 3383092, 3005795 and 3533930 disclose dry or non-lubricant processes¹. U.S. Pat. No. 3,226,581 discloses the use of filler leachable particles (colloidal alumina, sodium chloride, ammonium carbonate) which are removed after preparation of the composition by an extraction and / or leaching method to form the desired porosity. In addition, the resulting fibril matrix is ​​made of PTFE and does not contain sorption particles for separation purposes.

U.S. Patent No. 3,351,020 and GP 993,193 disclose the preparation of a PTFE film by compression followed by rolling or stretching. A liquid lubricant that is mixed with polytetrafluoroethylene, such as naphtha, gasoline, petroleum alcohols, glycerin, and other organic liquids, can be used up to 50 volume percent filler. The film is used for the production of shaped articles.

The essence of the invention

The present invention provides, in brief, a PTFE composite article comprising:

-4a) a polyteraflufluoroethylene (PTFE) fibril matrix a

--b -); insoluble, non-swellable- sorption particles introduced - into .....

said matrix, wherein the ratio of non-swellable sorption particles to PTFE is in the range of 40: 1 to 1: 4 by weight, and the composite product has a porosity in the range of 30 to 80 percent expressed as void volume and a mean pore size in the range of 0.3 up to 5.0 micrometers.

In another aspect, the present invention provides a method of controlling the porosity and mean pore size of fibrillary semi-rigid composite fibers such as ETEE. with chromatographically active non-swellable sorption particles evenly distributed but not adhering in PTFE. These products can be prepared from chromatographically active non-swellable sorption particles and PTFE emulsions by improving the procedures set forth in U.S. Pat. 4153661 so as to improve the porosity of fibril products. An improved method for producing composite layers includes · steps:

a) mixing the lubricant. with a mixture containing insoluble, non-swellable, sorption particles and polytetrafluoroethylene. to form a soft dough mass, the lubricant being present in an amount exceeding the spray capacity. The lubricant particles are at least 3 weight percent up to the amount at which the mass loses its integrity, has a cohesive consistency, and the ratio of insoluble particles to PTFE is in the range of 40: 1 to 1: 4.

b) vigorously mixing said mass at a given temperature and for a sufficiently long time to cause initial fibrillation of said PTFE particles;

c) bisxial calendering of said mass in the calender slots. rollers maintained at a temperature for a given time and closing the gap between the calender rolls during each further calendering operation causing further fibrillation of said PTFE particles and the formation of a self-supporting, structurally strong layer.

Advantageously, this improved method involves an increased amount of lubricant.^- hě fiem. processing^— ta á by⁷ the lubricant was present in an excess of at least 3% by weight to 200% by weight relative to the sorption capacity of the lubricant particles, more preferably at least 5% by weight up to 300% by weight, even more preferably at least 25 to 200% by weight and most preferably at least 40% by weight. up to 150% by weight of excess in excess of the sorption capacity of the lubricant particles.

' 5^alS It is an aspect of the present invention to provide a general method using particulate-filled membranes for clinical, biological and environmental analyzes, wherein the void volume of the membranes is controlled by the amount of lubricant used in the manufacture of these products. ^_These membranes are suitable for both size-exclusion filtration separations and molecular sorption chromatographic separations.

In such applications of this product, the advantage is that the even distribution of the particles in the matrix eliminates the undesirable presence of channels, which is known in the art when using finished columns / beds through which solutions pass. The separation and chromatographic products of this invention are useful in chemical and biochemical separations / purifications.

In this specification, controlled porosity means an open structure containing an empty volume designed to obtain an optimal flow of liquids and gases for efficient chromatography.

for efficient separation and separation of the mixture into its components;

-6empty volume means empty space in the structure of the composite, -material, ·· ..... .....................------- - ---- matrix means an open structure of intertwined mass. microfibers;

hydrophobic Particles means particles with low surface polarity, i.e. in the range of 0.1 to 0.5, semi-rigid means flexible, spatially stable and non-adaptable; folding results in rupture, · ceramic means non-metallic, inorganic materials, normal phase system means more polar stationary phase, and less. PO.l.érní_mo.bile_f.éz.i._;.

a reverse phase system means a less polar stationary phase and a more polar mobile-phase,.

non-swellable particles means particles having a volume change of less than 0.5, preferably less than 0.1, most preferably less than 0.01, where Vg is the volume of the particle after swelling and Vo is the volume of the dry particle in the formula (Vg - Vo) change volume - —— ——

- Vo '

Particle or particulate means solid shapes (excluding PTFE) having a diameter of 0.1 to 200 micrometers, preferably 5 to 40 micrometers with a size ratio of 1 to 1 00000, except for particles as defined below. Properties modifying particles means those particles which, during chromatographic and separation applications, have essentially no sorption properties and which modify the surface energy of the particles, for example these particles retain the hydrophilic properties of the product, they increase the tensile strength or make the product more fibrous, net surface energy means the sum of polar and non-polar surface energies, self-supporting means that no solid support is needed for the product,

-7 layer structurally "solid" means that it is linear. "non-volatile, sorbent or sorption" means the ability to absorb and be absorbed either by absorption or adsorption, "~" "i: ubr ± k''aM '" "žh ^ myna" j ^^ riŤ ^^ á^-bgzr^rOrganic and liquid liquids, or combinations thereof, used in the preparation of a composite product, and the sorption capacity of the lubricant means the amount of lubricant required to saturate the mass of particles.

The present invention provides a porous, fibrillated article comprising PTFE and a method of making the same. The porosity and void volume of the product depend on the amount of lubricant used in the manufacture of the product.^tíIt has been found that the amount of lub-. used in fibrillation processing is directly related and controlled. the percentage of void volume as well as the average pore size. As the amount of lubricant increases, the void volume and average pore size also increase as shown in Figure 3. Critical parameters for products used in separation processes are void volume and pore size because these parameters control filtration flow times and solvent migration ratios in planar chromatography. These products are suitable for analytical and preparative purposes in the art, separation and analysis in the clinical, biological and environmental fields.

Hitherto, those skilled in the art of separation have selected sorption chromatographic particles operating in a normal phase system or in a reverse phase system or preparing their groupings depending on the material to be separated and / or purified, the particles being introduced into a column chromatography tube or applied to a substrate such as a glass or plastic plate for planar chroipatography (TLC usually uses glue or gypsum particles)

-8as hydrated.calcium sulphate to bind particles on the board); ............- ............ ··· ........ The present invention provides practical and efficient chromatographic products and methods for their preparation that can be used either in a normal phase system or in a reverse phase system or a combination thereof in either membrane or layer form. so in a columnar arrangement. The effectiveness of these forms is determined by the control of the porosity of the chromatographic material, which is prepared using specific amounts of lubricants and P-TJ-E-matM-oe ratios. and normal / reversed phase sorption particles which are intimately mixed in the prepared chromatographic products according to the invention. The increase in the amount of lubricant during processing of the product containing PTFE / particles has. resulting in an increase .. void volume and mean pore size in the final product. There has been no indication in the art that the amount of lubricant controls porosity as stated in the present invention. The effect of the lubricant, as now found, is to provide an incompatible medium in which the particles are maintained relative to each other. separated from each other and forming pores in the product. To date, the role of the lubricant has not been recognized. Additives such as salt, sugar or ammonium bicarbonate have often been used. incorporated into the PTFE matrix and then eluted with solvent to form voids. spaces or pores.

. The controlled amount of lubricant provides predictable and reproducible porosity and performance parameters (eg, rise time, fluid flow). Those skilled in the art of separation are aware of the importance of particle surface area, packing density, and particle size homogeneity in the production of separation media. For the first time, it has now been found that the lubricant content in the processing of PTFE-containing products according to the invention has a direct and controlling effect to provide excellent and consistent separation properties.

-9Controls the amount of lubricant during fibrillation of the composite PTFE product. Controls the pore size and void volume of the final product. Increasing the amount of lubricant so as to exceed the sorption capacity of the particles - for the lubricant by at least "3" by weight, preferably by at least weight percent, more preferably at least 25 weight percent and most preferably at least 40 weight percent and up to 200 weight percent, provides a mean pore size for the final product in the range of 0.3 micrometers to 5.0 micrometers, preferably 0.4.33 5.0 micrometers, even more preferably 0.5 to 5.0 micrometers and preferably at least 90 percent of the pores are less than 3.6 micrometers in size, more preferably at least 50 percent of the pores are less than 2.5 micrometers. The void, volume and mean pore size vary directly depending on the amount of lubricant present in the fibrillation treatment, all other variables remain constant and include the amount of PTFE and particles (size and type) mixing time, temperature, number of bends during calendering, cylinder gap and type lubricant. These other variable parameters may affect the porosity, but do not have a precise lubricant control effect. The amount of suitable lubricant can vary depending on the origin of the particles and it has been found that increasing the amount of lubricant during processing increases the total volume, pores and mean pore size. Increased pore size and increased mean pore size result in reduced solvent rise time and reduced flow time.

The inventors have found that a precisely controlled amount of lubricant during the manufacture of the products of the invention provides products having unexpected and highly desirable properties, as mentioned above, the composite products of the invention have excellent separation properties with increased solvent uptake and filtration rate.

What has not been known in the art to date, but what the authors of the present invention have demonstrated, is the ability to control porosity .... products containing -ETFS with "incorporated" particles "without" the use of leachable materials . The authors have discovered that the amount of lubricant selected can be used for control. porosity and void volume in an accurate manner, which was not yet known. This is a specific advantage when using this product in separation applications, including extraction, separation and purification, where the process includes the flow rate and flow rate of the liquid through the product.

- -F-epi-s — drawings ----_;---— Fig. 1 is a photomicrograph (100x magnification) of a composite article according to the present invention with a matrix formed; PTFE fibrils into which chemically and / or physically active, sorbent, non-swellable particles are introduced.

Fig. 2 is a graph of pore-percent versus pore size in a composite layer according to the invention.

Fig. 3 is a graph of cumulative pore percent versus pore size for a series of composite articles of the invention prepared by controlling the amount of lubricant in the formulations.

Fig. 4 is a graph of solvent migration times for thin layer chromatography; (TLC) depending on the different average porosity of the products obtained with different amounts of lubricant in the manufacture of the preparations.

Fig. 5 is a graph of the filtration times of liquids through composite formulations versus different average porosity formulations obtained with different amounts of lubricant in the manufacture of composites.

1.Detailed description of pictures

Giant. 1 is a cross-sectional photomicrograph of a 0.5 mm thick composite article of the invention showing fibrillated PTFE® particles^-latex^-b ^ diameter^— Γ5^- mŤkrbmatrůV ^ Teríúb^-The product contained 20 percent PTFE and 80% particles by weight and was prepared by the procedure described in Example 1. These PTFE fibrils⁴ the particles and the small diameter of the fibrils, the small surface area and the sorption inertness block really few sorption sites of the particles. The sum of the space between the particles forms the empty volume of the product. In this case, the void volume was about 60 percent of the product volume.

Fig. 2 is a graph of the percentage size distribution ppr of a formulation using a controlled amount of lubricant in an amount of 120 weight percent lubricant relative to particles for the purpose of controlling porosity (Sample 2A, Table 1). Pore ​​size measurements were performed using a Coulter Porometer as described in the examples. The smallest pores present were at least 0.2 micrometers in size and the largest pores would be less than 1.7 micrometers in diameter. The average pore size was 0.5 micrometers.

Fig. 3 is a graph showing cumulative percent pore sizes. measured with a Coulter Porometer to control the amount of lubricant used relative to the amount of particles (105 weight percent (A), 135 weight percent (Β), 160 weight percent (C), 200 weight percent (D) / a shows that the amount of lubricant controls the porosity (mean pore size) and the void volume of the composite formulation, These data are obtained from Samples 1A, 3A, 1G and 3C, prepared as described in Example 1. The porosity of the mean pore size and the void volume control the migration rate of the solvent in the plenary chromatography and the flow rate in the filtration / extraction method of use.

Fig. 4 is a graph showing the effect of my amount of treated lubricant (from Table 3) ng solvent migration rate or the time required for the solvent front to reach 50 mm from the start in planar (ILCLC) chromatography. The particles used were silica gel (medium size 8 micrometers) and the solvent used was dichloromethane with 0.5% by volume of methanol. These particles have a sorption capacity for the lubricant of about 75 percent by weight of the particles. The solvent migration rates (in minutes for '50 mm solvent migration) for this chromatographic product were:

Migration rate (min, 50 mm migration) of the lubricant mass

8.3 - 14.5 (preferably) 140-200

8.3 - 10.5 (more preferably) 160-200

8.3-8.8 (most preferably). 180-200

If the amount of lubricant during processing is too low, the migration time of the solvent is too long and the resulting product has little practical use as a chromatographic medium. The amount of lubricant. used — to — processed-i-, r ~ \ f \ c r + π “j · Τ nf ττ -n /“ <, Vzdálenost-ί g Ir o mn X π η ττ Yirirjnonc + QÓlo v ů u tj ic umu o iaíx ixxitxx <ur dixp jr xvv Vw-uxw w mm distance less than 12 minutes is most preferred and corresponds to about 160 percent by weight ratio of lubricant to particles and mean pore sizes around 18 «

Fig. 5 is a graph showing the effect of the amount of lubricant treated on the flow rate expressed as filtration time (47 mm diameter reverse phase disk) for one liter of reagent water samples (samples 2A, 3A, 4A, 50). Cg. this graph is typical. for non-swellable particles, e.g. silica gel, modified silica gel, zirconia, coated zirconia, crosslinked resin particles such as XAD (Roohm and

Haas, Philadelphia, PA), Tenax¹^ (Supelco, Bellefonte, PA)

-13a nylon. The dependence of the pore size of a 0.5 mm thick disk containing modified C8-silica gel in a flow-through arrangement on the weight percentage of lubricant (relative to particles) was as follows:

Particle size (micrometers)

0.5 2.5 (preferred)

0.5 -1.7 (more preferably)

0.7-1.5 (most preferably)% by weight of processed lubricant

120-200

120-160

130-150

Flow times are directly dependent on the porosity of the product, which depends on the amount of lubricant processed. More desirable are flow times of less than 30 minutes per liter, which corresponds to about 120 weight percent of lubricant to solid particles and a mean pore size of 0.51 micrometers. The most suitable product thicknesses are in the range from 0.1 to 10 mm.

..Detailed description of preferred embodiments

The composite PTFE products of the present invention have a void volume in the range of 30 to 80 percent. This void volume can be achieved by using a lubricant in an amount in excess of at least 3 weight percent to 200 weight percent of the sorption capacity of the lubricant particles. Preferred mean particle sizes. For separation applications are in the range of 0.3 to 5.0 micrometers and preferably 90 percent pores smaller than 3.6 micrometers, 80 percent smaller than 3.2 micrometers, and 50 percent pores smaller than 2.5 micrometers. More preferred mean pore sizes are in. in the range of 0.5 to 5.0 micrometers and most preferably in the range of 0.4 to 5.0 micrometers. The preferred void volume is in the range of 40 to 70 percent, still

-14 most preferably in the range of 50 to 65 percent and most preferably 5'0dc 60' percent '· ........... ..... .... ......... .

The preferred ratio of non-swellable sorption particles to PTFE is in the range of weight ratios. 20: 1 to. 1: 2, more preferably in the range of weight ratios 19: 1 to 1: 1.

The particulate material (which may be a single substance or a combination of substances) suitable for use in the present invention is substantially insoluble in water or in an elution solvent. -sYe — v-i-ee-'than-one-gram-č-ás-tic — se-^ ozpu-s-tí — v-e_3D.0_g. medium or elution solvent when mixing the particles. at·. 20 The material of the particles may be at least one of organic compounds, a polymer or inorganic oxides such as silica and zirconia, other ceramics, combinations of these substances, or it may be an ion exchanger or chelating particles or mixtures thereof, or it may be carbon . The preferred particulate material is silica and zirconium dioxide, with silica being particularly suitable for the ease with which various hydrophobic and other modifying functional groups can be attached to; its · surface and for its commercial availability. particles such as silica and other inorganic oxides are commercially available, for example, from Aldrich Chemical Co., MilvJaukee, V / I. Zirconia is available from Z.Tech Corporation, Bow, NH_E

Suitable material, referred to for the purposes of this invention as particles, includes any Particles with intrinsic sorption properties or particles that can be coated with a substantially insoluble sorbent material or a surface, internal or external, that can be modified to form. would be a substantially insoluble coating-sorbent material. Conveniently. carriers for these coatings include inorganic oxide particles, most preferably silica particles.

These insoluble sorption coatings generally have a strength in the range of one molecular monolayer to about 1 micrometer. ¹These coated particles are well in the art.

known, see for example Snyder and Kjrfciand, Introduction to _ffodérn-Licuid Chromatographv, · 2_Eed., John Wileyand Sons, Inc. (1579) and H. Figge et al., Journal of Chromatography 351 (1S & 6) 393-408. These coatings can be formed mechanically by in situ crosslinking of polymers, or, these coatings can be. formed by functional groups covalently bonded to the surface of organic or inorganic particles. Photases that can be applied to silica particles can be non-swellable polymers such as crosslinked silicones, polybutadienes, etc., or covalently bonded organic groups such as aliphatic groups of various chain lengths (e.g., C₂H 2, C 2 H 2, and aliphatic and aromatic groups containing amine, nitrile, hydroxyl, chiral and other functional groups that alter the sorption character of the coating. Such coated particles are commercially available (e.g., Gg modified silica gel, Alltech, Deerfield, IL). .

If silica or another carrier particle is used to produce the coated particles, it acts primarily as a carrier or substrate, and the coated particles are generally non-swellable even when swellable thin layers of coatings are used. The composition of the coatings allows for variability in chemical selectivity and efficacy, as is known to those skilled in the art.

The particles may have a regular shape (e.g. spherical or cubic) or an irregular shape. The particles that have been found to be suitable for use in the present invention have an apparent size in the range of 0.1 to about 200 micrometers, preferably in the range of 1.0 to 100 micrometers, more preferably in the range of 5 to 40 micrometers. . In some

In some cases, it has been found that it is advantageous to use particles in - dv o u-or o -v-í c er o z-me-r e ch- č È, - sp ad a jic ich 'do' š i year range. Examples are particles having an average size in the range of 0.1 to 100.0 micrometers of chromatic efficiency, which can be used in combination with particles in the range of 0.1 to 250 micrometers, acting as a property modifier. These modifiers can alter the color, hydrophobic properties, wettability, phosphoescence and fluorescence properties, and similar properties of the composite product. robku. There may be some reduction in particle size, such as mixing of the andes. ~ v. depending on the friability of the particulate material. While the original particles may initially be larger_r they can be reduced to finer particles in the final form without side effects.

water capacities suitable for use according to the invention have a water sorption capacity of less than 10% by weight, preferably ≥ 1% by weight. As noted above, particles that are subject to spatial variation due to water swelling are less desirable in terms of information. z-US patents

4565663 and 4,460,642, it is surprising that hydrophobic and other non-swellable particles incorporated into PTFE provide more advantageous chromatographic products compared to water-swellable particles incorporated into PTFE.

In contrast to the prior art, the inventors have surprisingly and unexpectedly found that with changes in the amount and use of excess lubricant commonly used to facilitate the incorporation of additional and auxiliary particles into the PTFE matrix in the manufacture of PTFE composite articles, porosity can be controlled. , empty volume and achieve the desired results.

This makes it possible to achieve increased and controlled porosity in PTFE composites without the use of contaminating extractable / leachable fillers, which is important for the performance of composites used in the field of separations »

-174- ------ J ~ - rr <? χ i .. · £ ιις · Λ <<< χ. '^₊· Uaa jr; LÍVCU.CX1U In uů paicHiu u · “tujuai, axb ± vux CfcStl— ce sorbents can be premixed with a property modifier. Representative of non-swellable property modifiers (some of these substances can be dissolved in water) can be -pOt and women-part of the cem-tic e-i-on-exchangers -, - uhi-ič-it an— in ápen-a-tý-_rAmmonium carbonate, kaolin, sugar, polyethylene, polypropylene, polyester, polyamide, polyurethane, polycarbonate, zeolites, chitin, vermiculite, clay, ceramic materials, chelating particles and the like. These property modifiers may be present in amounts ranging from 0 to 28.99 parts per part of PTFE, more preferably above 0 to 9.00 parts per part of PTFE, provided that the sorption non-swellable particles plus the modifier particles do not exceed a ratio of 29 parts particles to 1 part PTFE. These ranges are desirable to achieve a preferred tensile strength of the composite structure of at least 0.01 MegaFascal (IvPa).

Additional water-non-swellable property modifiers can be advantageously added to the mixture of aqueous PTFE dispersion and primary particles to provide further improvement or modification to the composite articles of the invention. For example, the modifier particles can form, chromatographically inactive materials such as glass beads with a small specific surface area, which can act as an aid and contribute to the fibrillation process.

It may also be appropriate to use a limited amount of water-swellable property modifiers (i.e., up to 30 weight percent, preferably less than 25 weight percent, more preferably less than 10 weight percent, and most preferably less than 1 weight percent based on the total particle weight). These swellable modifiers also include starch, chitosan, modified starches such as Sephadex®._and Sepharose® (Pharmacia, Sweden), agarose, polymethacrylates, certain copolymers of styrenedivinylbensene, polyacrylamides, celluloses as cellulose fibers and coated particles (e.g. silica-poly-18-acrylamide coated silica). Water-swellable substances can be used to form thin-film-non-swellable particles to form non-swellable particles for chromatographic purposes.

AND

... When using hydrophobic particles, a preferred method of making the composition of the invention utilizes a PTFE emulsion with a property modifier added to increase the surface area of ​​the hydrophobic particles / to interact with water and allow rapid wetting of the surface of the hydrophobic particles. Preferred modifiers for this purpose are organic substances such as alcohols, amines, acids and the like, with the advantage of the alcohols, especially in their easy removal, for example by extraction. solvent or drying after manufacture of the preparation.

In terms of surface energy, it is desirable to minimize the amount of PTFE and sometimes vary the amount of active particles. ^bThe refractory or fluorescent particles may be added in small amounts (up to 10 weight percent of the particles) to detect separated components of the sample or components to be separated. Chemically active particles that indicate the chemical properties of the α-pH of the separate oblique bands. mixtures may be suitable for diagnostic purposes. ' ^rThe process according to the invention represents an improvement over the prior art. Specifically, the composite PTFE product of the invention is made by mixing the particles used or a combination of particles, PTFE and lubricant until a homogeneous mixture is obtained. The PTFE and lubricant can be added in the form of a PTFE resin emulsion, which is commercially available from DuFont. It was found that to optimize the separation properties of the final product. would be the amount of lubricant in the mixture or lubricant further added, i. water or aqueous solvents or organic solvents should be present in an amount sufficient to exceed the sorption capacity of the lubricant particles by at least 3 weight percent up to 200 weight percent, more preferably in the amount

- Exceeding the sorption capacity of the Lubricant Particles in the range of at least 5 to 200 weight percent, more preferably at least 25 to 200 weight percent, and most preferably at least 40 to 150 weight percent. lato 'ov aTíé ^ s t'ředn í “

- r cz months - can ^-* σρ ti ma ± ř sovět^-ρ r^_O^—form a pore size for different types of particles and for different types of ordered types of separations. For the lubricant / C-8 system · modified silica gel, b. The lubricant should be present in the range of 103 to 200 weight percent relative to the solids in the PTFE composite article, preferably 105 to 200 weight percent, more preferably 110 to 180 weight percent, and most preferably 115 to 175 weight percent.

Due to the many differences in the sorption capacity of the particles for the lubricant, the amount of lubricant will depend on the type of particles allowed, functionalized or derivatized organic resin systems such as sulfonated cation exchanger, optimal or most preferred range of lubricant amount is 150 to 200 weight percent based on particle weight .

Suitable lubricants in the process of the invention may be water, aqueous solvents such as water-organic solvents, e.g. water / alcohol in any ratio, preferably in the range 4: 1 to 1:40, more preferably 1: 1, where the alcohol it may be any alcohol which can be conveniently removed by washing or drying, where the preferred alcohol is a C 1 to C 4 alkanol, or other organic solvents such as ketones, esters and ethers which may be suitably removed, for example by washing or drying.

Simultaneously with the controlled dosing of the amount of lubricant exceeding the sorption capacity of the particles for the lubricant by at least 3 percent by weight to generate the desired porosity value of the final product, mixing takes place. The aqueous PTFE dispersion can be mixed with a mixture of particles (containing property modifiers and excipients) to form a mass,

-2 0 having a soft consistency similar to putty or dough. The solids capacity of the mixture for the formulation is determined to exceed at least the amount required when slight additions of lubricant can no longer be incorporated into the mixture without separation of the mixture, which conditions should be. be maintained throughout the mixing operation. Soft putty-like substance. is then subjected to intensive mixing at a temperature of up to 90 ° C, preferably, v. in the range of 0 to 90 ° C, more preferably in the range of 20 to 60 ° C for a time sufficient to. causing initial fibrillation of PTEE particles. To obtain chromatographic

It is necessary to minimize mixing at a given time. (-trarLs-par-t-ni-eh-vl-as-t-nos-t-i - (- for example - flow-through-in-plants)). temperature.

Mixing times during processing usually vary from 0.2 to 2 minutes so as to obtain the necessary initial fibrillation of the PTPE particles. Initial mixing causes partially disoriented fibrillation of a substantial portion of the PTFE particles. Optimal initial fibrillation is achieved about 90 seconds after reaching the point where all components have been fully incorporated into the putty (dough) consistency. Shorter times or periods exceeding this point provide a composite layer of poorer chromatographic properties.

The intake mixers are municipalities used for this necessary intensive rate-intensive mixer, sometimes referred to as an internal mixer, a kneader, a twin-blade mixer, as well as an intensive mixer and a twin-screw extruder. The best known mixers of this type are mixers with a sigma blade or arm, they are fed

CNSrabender. TM. aer mixer ..

Some commercially available mixers of this type, in, TM, ÍM.

under the designation ^ anoury mixer, mogul mixer, ~ TM.

r-rep mixer and sigma can also be used paddle G.sí.Brabend other suitable intensive mixing equipment.

The soft, putty-like mass is then transferred to a calendering machine. The mass is then subjected to biaxial calendering between the slots of the calender rolls while maintaining a temperature of up to 125 ° C, preferably in the range from 0 to 100 ° C._T3-t is more preferably in the range of 2-G to the next fibrillation of said PTFE particles to form a self-supporting layer and to close the slits. between rollers in each subsequent calendering operation, for a time sufficient to form a structurally resistant layer preferably having a tensile strength of at least 0.01 MPa, more preferably at least 0.05 tPa. the resulting layer is optionally subjected to drying to remove the lubricant, and the resulting composite layer comprises a network of interwoven PTFE microfibers forming a fibril matrix with incorporated sorption particles. The amount of lubricant in the mass is maintained at least such that it exceeds the absorption capacity of the solids by at least 3 percent until sufficient fibrillation occurs and the porosity or void volume reaches at least 30, preferably 40 to 70% of the total volume. The preferred amount of lubricant is determined by measuring the pore size of the product using a Coulter Porometer, as shown in the examples below. Increased amount of grease result, increased pore size and increased void volume.

The PTFE aqueous dispersion used in the manufacture of the composite layers and other products of the present invention is a milky white aqueous suspension of fine PTFE particles. Typically, this aqueous xxxxx dispersion contains about 30% to about 70% by weight of solid particles having a particle size in the range of about 0.05 to about 1.5 micrometers. Commercially available aqueous dispersions. of the PTFE may contain other additives, such as surfactant, those and stabilizers to maintain this suspension of PTFE particles. For some applications, it is advantageous to remove the surfactant by extraction or to select a surfactant-free emulsion.

These aqueous PTFf dispersions are currently commercially available

-22t available from EIDupont de Nemours, for example under,. ; TTVI TM TM. trade names. .TefIon. 3.0., ... Teflon^{1 w}.3.0B .. or ..Teflon. 42 ... · ”'. Tm tm '^xeflon 3.0 and Teflon^x 3OB contain about 59% to about 61% by weight of solids, which make up the majority of PTFE particles. 0.05 to 0.5 micrometers in size and 5.5 to about 6.5% by weight (based on the weight of the PTFE resin). nonionic wetting agents, usually octylphenol, polyoxyTM ethylene or nonylphenol polyoxyethylene. Teflon 42 contains about 32 to 35% by weight of solids and no wetting agent, but has a surface layer of an organic solvent to prevent evaporation. It is generally desirable to remove any residual surfactant or wetting agent after manufacture of the product to avoid possible interference during separation. a. Chromate for graphic applications.

The present invention provides a novel composite product and a method of making the same, preferably the composite structure is a homogeneously porous composite layer comprising water-non-swellable particles homogeneously distributed in a matrix formed by intertwined PTFE fibrils. In this structure, almost all the particles are separated from each other ·· and each is isolated and does not stick to each other or to a cage-like matrix that keeps the particles in all directions by a network of PTFE microfiber fibrils, as shown in

Figure 4. A preferred novel layer according to the invention has a thickness in the range of 100 to 10,000 micrometers, preferably 125 to 5,000 micrometers, even more preferably 150 to 2,500 micrometers and has a limit. tensile strength of 0.01 íPaPa and even as high as 5.0 íPaPa.

The composite product has a substantially uniform porosity and is thus suitable for chromatographic use, which may be in the form of a single self-supporting layer or a combination of layers to form layered plates / columns or as a composite applied to an inorganic support such as metal or glass, or on an organic support such as paper or polymers. Laminated boards / slcppce may contain layers of composites of different porosities. Controlled porosity is an essential feature of this composite product to achieve suitable chromatographic performance.

A first use where this PTFS / particle technology may be beneficial is to use the composite product of the invention to preconcentrate and isolate certain substances prior to further analysis by various analytical procedures such as gas or liquid chromatography. In this flow-through method well known in membrane filtration and solid phase extraction, the flow of solvent and sample is conducted in

at an angle of 90 degrees to the surface of the board. .It. is a conventional arrangement where the separation path is equal to the thickness of the layer and the thickness of the matrix, the separation length can be increased by layering other layers, but these layers are not tightly bonded as calendering is limited to a specific thickness. This method is efficient for single-stage or multi-stage adsorption-desorption separation. This method is also effective when using reactive particles, ion exchangers, chelating materials, or sorbing the particles using normal / reverse phases or combinations thereof.

The utility of the membrane method can be increased by including many other reactive particles to perform the desired chemical and physical separations. Such a product strongly sorbs the component to be isolated from the mixture to the active particles of the composite product and the other components are not sorbed (passing through the membrane) or are eluted by the first solvent. The second solvent, which has a larger. the affinity for the isolated component than for the particles is then used to replace the desired component in the Particles and allows the component to be obtained in a more concentrated and purified form.

In the second method, the flow is parallel to the surface or has a zero-angle to the edge or a longitudinal dimension. . The length of the separation can be chosen depending on the dimensions of the product used and the flow rate depends on the ability to transport the solvent by capillary action or forced flow (application of external printing). In order to obtain a high resolution chromatic separation, multiple serpentation and desorption steps requiring a minimum separation path are required, which is not practical in a columnar arrangement by laminating the discs of a composite preparation. In this case, a product suitable for analytical and preparative separations carried out similarly to TLG or planar (PC) chromatography, where the solvents and components of the sample are normally transported. medium by capillary action, but it is also possible to use forced flow.

The rate of solvent migration or elution with the composite product is believed to be porous and is also affected by total surface energy, PTFE fibrils, chromatographically active particles such as silica gel and all modifier particles. Small amounts of PTFE appear to be dominant in their contributions. to the total surface energy and to the migration rate of the eluent. This can be due to the stayb and the method of manufacture of this product, where the active silica gel particles do not touch each other.

of the elution solvent are dependent on the low surface energy of the PTFE fibrils. In a preferred embodiment, using silica gel particles, several experiments were performed with different ratios (silica gel / PTFS) ranging from 55/5 to 80/20 and it was found that the higher silica gel content accelerated the migration of solvent and components. This velocity appears to be a function of the total surface energy of the composite layer.

The total surface energy of the composite product is given by the weight average surface energy of the PTFE matrix (^Epijpg)>

-25 active sorption particles (E and modifier particles ^EIt is desirable that the total surface energy be in the range of 20 to 300 milliNewose per meter, preferably 50 to 300 niN / m. This ensures optimal surface energy for _ · _ „________{_} .-- 1. . ι -.--------- ---- '-'--: transport of solvents and solutes, the total surface energy of the particles includes polar and non-polar forces. Polarity is given by the ratio of polar surface energy to total surface energy. For example, the polarity of PTFE, Nylon 66 silica gel calculated from surface force data is 0.10 ·,

0-, 21 'and 0.38.

The composite products of the present invention have a high sample loading capacity and can be very suitable for preparative or production chromatography. The migration rate of the eluent (solvent) can be significantly increased by using radial chromatography using a central force to force the solvent through the porous chromatographic product. This procedure is well known in the art. In addition, it has been necessary in the art to use a larger amount of wedge or binder to bind a chromatographic material such as silica gel to conventional cast glass plates, while products. According to the present invention, composite fibrillated PTFE articles do not require any binder or backing plate. Hitherto in the art, particles that adhere satisfactorily to a glass plate have been limited to silica gel and alumina. The present invention has the great advantage that virtually all organic and inorganic particles can be trapped in the fibrillated PTFE matrix for many chromatographic applications. It is not necessary to use any binder. The absence of any binder is of particular importance in reverse phase systems with bubbling hydrophobic particles. . The composite chromatographic products according to the invention can have different sizes and shapes. Preferred products are similar to layers forming discs or strips. Coating of non-swellable particles with a very thin (monolayer) layer of substances

-26 or thickeners, which provide in situ crosslinking of polymeric covalently bonded functional molecules to the surface of the particles, allow the optimization of both chromatographic selectivity and separation efficiency. '. The composite articles of the present invention have utility in many physical particle size separations and in chemical sorption separations where the selected particle material is suitable for controlled filtration according to the size or molecular range of the static exclusion. These products have the use of single-packed or multi-packed desorption separations of descriptors to immobilize reactive particles. to perform chemical or biochemical diagnostic reactions, to exchange ion exchangers, and to isolate cations and anions, to purify substances, for chromatographic separations and analyzes in both positive and forced flow, for hydrophobic reverse phase and normal phase chromatography. In all the examples described, the critical factor in the chromatographic performance of the products is controlled porosity.

In particular, embodiments of the products of the invention may be useful in environmental analysis in the recovery or isolation of contaminants, including toxins and pesticides, etc., from air, water, soil, food and beverages. Me-; The motor products of the invention may be useful in clinical applications in the isolation and thickening of drugs, metabolites, etc. from biological fluids.

The object and advantages of the present invention are further illustrated by the following examples, but the material of the particles and its amounts given in these examples, as well as other conditions and details, should not unduly limit the present invention. In the examples, all composite materials prepared according to the invention contained the addition of a lubricant in an amount exceeding the sorption capacity of the Particles in the range of -273 to 200 weight percent. Parts and percentages in the examples are by weight unless otherwise indicated.

Examples of embodiments of the invention

Example 1

In this example, a series of composites was prepared using an improved procedure as described in Example 2 of U.S. Patent No. 4,810,381. In this case, in addition, the amount of lubricant (1 part water / 1 part isopropyl alcohol) was carefully controlled to produce products having different porosities. .

For sample 1A, 10 grams of

Cg of modified silica gel (Analytiplchem ​​Int., Harbor City, CA). These particles have a sorption capacity for the lubricant of about 75 percent by weight of the particles. 1.6 g of polytetrafluoroethylene (RFF) resin resin (TefT 1), ion pO 3, NiDupont, Inc., Uilmington, Del., Were added sequentially in three portions with alternating vigorous stirring. This increased the ratio of modified silica gel C to FTFE 50/10. Temperature

O..

'C, preferably in the range, may then be increased up to 20 '20 ° C, more preferably to about 23 ° C. If it was added successively in three portions with alternating vigorous stirring

10.5 g of lubricant. After these substances were intensively mixed, a semicoherent mass was formed having sufficient physical cohesion to remove the entire contents of the beaker as a uniform mass. The above mass was then placed between two rollers, the temperature of which was maintained at 50 ° C. It is also possible to keep the rollers at a temperature of up to 125 ° C, preferably 0 to 100 ° C and even more preferably 20 to 60 ° C and with a slit of about 1.5 cm to form a strip of cohesive product. translated to the next layer^:and then allowed to pass through the rollers after turning 90 ⁰ relative to the previous direction of passage. This cyclic process of folding and rolling in a direction rotated 90 ° from the previous pass was repeated several times to form a rigid, strong, flat piece of material.^IjThis material was then calendered in the direction of the longitudinal axis of the cylinders with gradually decreasing ones. st.er.bini to form a continuous belt. This strip was then folded to form a multiple layer, which was then drilled as before, but in. the calendering direction rotated 90 ° from the previous one.

The calendered layer of material was then allowed to air dry for 48 hours. The procedure described in Example '1' was repeated with increasing amounts of samples._rr2.A_r, „„ 3A., „4A) and the data on the formed composites are given in Table 1. The obtained results showed · that porosity can be achieved in a predeterminable way, without the use of extractable or leachable particles as. ε has so far stated in the field. The data show the minimum, mean, and maximum pore size distributions determined using a .Coulter Porometer (Coulter Electronics Inc., Edison, KJ) for various amounts of lubricant in the formulation. Figure 2 shows the pore size distribution of Sample No. 2A using a Coulter Porometer.

Table V

Effect of lubricant on the size distribution of feathers

<td>vžořekčg; "'</td><td>% lubricant ^X ‘ '</td><td colspan="2">pore size minimum- medium</td><td>sample (yum) maximum</td>

<td>1A</td><td> 105 </td><td> 0,115</td><td> 0,237</td><td> 0,859</td>

<td>2A</td><td> 120</td><td> 0,244</td><td> 0,5-11</td><td> 1 ,695</td>

<td>3A</td><td> 135</td><td> 0,470</td><td> 0,864</td><td> 2,680</td>

<td>4A</td><td> 150</td><td> 0,524</td><td> 0,972</td><td> 2,938</td>

^xThe water / alcohol lubricant values ​​listed in Table 1 are weight percent, lubricant to solids.

The data in Table 1 show that increasing the weight percentage of lubricant provides a product with larger minimum, medium and maximum pore sizes. Sample No. 3A proved to be suitable for the extraction of therapeutic drugs and their metabolites from the blood column with a recovery of more than 90%. of these substances. .

Example 2

This example illustrates the effect of cellulose used as a hydrophilic modifier in the form of particles mixed with silica gel on the resulting PTFE composite chromatographic product, which composite products were prepared with various amounts of lubricant (see Table 2 below) to control porosity as described in Example 1, except that 0.35 weight percent of cellulose fibers 40 micrometers in diameter were added to the particles in this procedure. The results are shown in the table. 2.,

A comparison of the data between Tables 1 and 2 shows the increased pcr-ozite resulting from the small addition (0.35%) of the cellulose particulate modifier, which is not extracted or leached from the composite product.

Hitherto, in contrast to the above, removable particles (by extraction / leaching) have been used as salts, extractable organic substances and the like to form a degree of porosity in the final product, cellulose particles have not been extracted and the inventors believe Furthermore, in the field of separation, and in particular in chromatography, it is very important to avoid the possibility of extracting foreign substances, which usually leave residues interfering in the trace analysis. In addition, experts will realize that it is actually impossible to completely remove traces of many extractable additives,

-30which interfere with the following analytical procedures in .many.seeds-less-than-one-per-trillion .-, ·· - ------------ Table 2

Influence of lubricant - on pore size distribution% of lubricant *

3B

4-B ·

105

120

135

-150 sample pore size (^ μm) minimum mean maxima_

0,214 ' 0,392 1,299

0,458 0,907 2,614

0.582 1.089 3.122

0.653 1.257 3j618. Lubricant values ​​water^ofThe alcohols listed in Table 2 are weight percent lubricants. to solid particles.

-F ^atThe data in Table 2 show that increasing the percentage of lubricant provides greater minimum, medium and maximum pore sizes. In addition, these data show an increase in pore size resulting from the use of cellulose as a property modifier.

Example 3

Example 3 shows the effect of the amount of lubricant on pore size, density, migration rate by TLC (including a comparative experiment), flow rate in a filtration arrangement, all of which are important for the chromatographic use of the product.

Table 3 lists the data obtained for five samples treated with varying amounts of lubricant (water / alcohol 1: 1) using the materials and procedures described in Example 1. Sample 5C was treated by a dry or lubricant-free process (U.S. Pat. 3864124).

-31Table 3

Effect of the amount of lubricant on the parameters of the layer

Sample% size density TLC time cT ~ ^ lubricant pbrů ^— (c / cn?) (min / 50 mm) filtration (medium (min / liter)

--_________________ /. um) .......... _ „_ ______

<td>1C</td><td> • 200</td><td></td><td> 2,50</td><td> 0,455</td><td> 8,32</td><td> 1,35</td>

<td>2C</td><td> 180</td><td></td><td> 2,00</td><td> 0,473</td><td> 8,83</td><td>1, S7</td>

<td>3C</td><td> 160</td><td></td><td>i, 76</td><td> 0,486</td><td> '10,50</td><td> 3,25</td>

<td>4C-.</td><td> 140</td><td></td><td> 1,17</td><td> 0,514</td><td> 14,47</td><td> 6,73</td>

<td>_5Cxx.</td><td> 0.</td><td></td><td> 0,29</td><td> —</td><td> 50,0</td><td> 68,6</td>

XX comparative ' ^xThe water / alcohol lubricant values ​​listed in Table 3 are weight percent of lubricant to solids.

As in Tables 1 and 2, Table 3 also lists the relationships between the mean pore size and the amount of lubricant. Ob- 'v

section 3 shows a cumulative distribution graph, pore size. each of the four curves represents data for samples of different amounts of lubricant, as detailed in more detail for samples. 1C-4C. The relationships between the amount of lubricant and the pore size distribution were clearly shown. These data indicate that the density depends on the porosity / void volume value.

the data in Table 3 also shows the relationship between the mean pore size, the migration rate of the solvent by TLC (0.5 volume percent methanol in dichloromethane) and the amount of lubricant. The most preferred rates by TLC are under 10 minutes for the 50 millimeter (min) path. Sample 5C prepared by the dry process provided unacceptably long migration dcbs, which is a direct consequence of the lack of appropriate porosity. That j understandable, as the subject of certain work in this field has been the preparation of non-porous products using a lubricant process. However, these products are well 'suitable' for chromatographic use because their porosity was so low as to impede acceptable solvent flow through the medium; In fact, (U.S. Pat. No. 3,121,124, column 17, lines 54-56), a fluid is passed through an unsintered mass to selectively desorb and separate chemical compounds. Figure 4 (/ gives s. table 3) shows the dependence Γ7θ ^ 1'υ3'Τι ^ ο ^ ρο'ΰ'3 * ΐ'έ'άΤ3 ~ 'ρ · Γί' ”Τ'ύΟ · '' · η9” ρΌηο · Ζ'τ1 · '2 As obtained with composite articles controlled by the ratio of lubricants to solid particles, times of less than 30 minutes, preferably less than 15 minutes, are most required to reach the front of the solvent to a distance. 50 mm from the start. One skilled in the art will appreciate that the separation / separation of the components of the mixture depends on the optimum rate of the solvent.

Table 3 also shows the data obtained for composite layers in waxed filtration for one liter of aqueous samples, the data for flow times are recorded in minutes per liter and clearly show the role of the use of the lubricant for filtration rates. The 5G sample made for comparison by the lubricant-free process is not acceptable because the lack of suitable porosity results in unacceptably long filtering times of a standard one liter of water sample.

The data in Figure 5 show the effect of mean pore size on flow times measured in the filtration or extraction method of use. A 47 mm disk was inserted into the filter.^T&lt;

iúillipore (millipore Corp., .Bedfort, MA).

Vacuum (26 inches of mercury) was applied and the resulting flow times for 1 liter of water contained were recorded. 330.5 percent methanol. The most useful range for the present invention is in the range of mean pore sizes from 0.5 to 5.0 micrometers. Most preferred is a mean pore size of 0.5 to 1.5 micrometers. The ability to control the size of the pores is particularly useful in the commercial use for the sorption properties of entrapped particles, allowing sorption separations or isolation at the molecular level.

Table 4 further shows the data obtained in a comparative experiment on the migration rate of the chromatographic solvent in use

1) a product - prepared essentially according to U.S. Pat.

4810381, Example 2, sample IQA (PTFE / silica gel 90/10 »a

2) of the product of the present invention as described in Example 3, sample 2C (PTFE / silica gel 90/10). Each of these products had a thickness of 500 micrometers, the solvent flow rates (0.5 percent methanol in methylene chloride) are shown in Table 4.

Table 4

<td colspan="4">Migration rates in chromatographic products</td>

<td>Values</td><td>mm. (motion)</td><td>comparative 10A (min)</td><td>according to invention 2C (min)</td>

<td> 1</td><td> 0,0</td><td> 0,00</td><td> 0, 00</td>

<td> 2 .</td><td> 5,0</td><td> 0,48</td><td> 0,22 -</td>

<td> 3</td><td> 10,0</td><td> 1,33</td><td> 0,68</td>

<td> 4</td><td> 15,0</td><td> 2,68</td><td> 1 ,27</td>

<td> 5</td><td> 20,0</td><td> 4,45</td><td> 2,02</td>

<td> 6</td><td> 25,0</td><td> 6,62</td><td> 3,02</td>

<td> .7. .</td><td> 30,0</td><td> 9,13</td><td> 4,10</td>

<td> 8</td><td> 35,0</td><td> 12,27</td><td> 5,37</td>

<td> 9</td><td> 40,0</td><td> 15,67</td><td> 6,97</td>

<td> 10</td><td> 45,0</td><td> 19,93</td><td> 8,80</td>

-34 The results shown in Table 4 show that the solvent flows. were, in the case of chromatographic products according to. .

of the present invention is more than twice as fast as the product of U.S. Patent No. 4,810,381, Example 2.

It will be appreciated that the controlled amounts of lubricant, water or water / alcohol mixture used in the formulation during the manufacturing process of the composite have a direct effect on the resulting pore size / void volume of the final product. It is apparent that a lubricant that is incompressible during the intensive manufacturing process of the composite article is responsible for the porosity and ability to control the pore size / void volume of the articles of the invention.

Example 4

This example illustrates a method of using a controlled pore size composite article in a flow sorption process. use. Insane porosity is important for the controlled flow of aqueous samples containing hydrophobic organics through the composite product in the form of a layer. Optimal flow rates are those where the flow rate is slow enough to quantitatively capture hydrophoric particles from the water, but also fast enough to allow adequate analysis times, preferably less than 60 minutes, preferably less. less than 60 minutes per liter of aqueous solution, most preferably less than 30 minutes per liter of aqueous sample, as shown in Example 1 for sample.2A.

The principle of this procedure is that when aqueous samples pass through the composite, the hydrophobic organic substances to be determined are trapped by hydrophobic particles.

After the aqueous solution has been treated in this way, these substances are recovered from the particles by passing a small volume of a less polar solvent (which is able to replace and dissolve the sorbed substances) through the composite. This same principle can be used

In many cases where it is desirable to extract hydrophobic organic substances from predominantly aqueous samples, such as analyzes of water pollutants (environmental analyzes) or analyzes of drugs and metabolites in biological assays, this is the case. I know the procedure. as solid phase extraction. This procedure is most suitable in the single-stage or multiple adsorption-desorption treatment described previously.

T. ¹

Heretofore, solid phase extraction using particle-packed columns or cartridges to capture organic matter (isolation step) has been reported in the art. Columns or cartridges filled with particles limit the control of porosity, since the porosity and thus the flow rate results mainly from the type and size of the particles. Furthermore, columns or cartridges filled with particles are subject to the formation of channels (open spaces or channels through which the aqueous solution of the sample can pass without interacting with the particles, as a result of which there is incomplete or insufficient isolation of organic matter from the sample).

In contrast, the present invention provides composite layers or membranes containing particles for isolating these organic substances in water or other organic solvents, where the porosity of the product can be controlled independently of the particle size and type. In addition, due to the structure of the product, ie. The particles are introduced into the fibrillated PTFE matrix, the formation of channels is prevented.

Table 5 further shows the data obtained when applied to · environmental contaminants such as 1-part-trillion pesticides (ppb), which were extracted from one liter of an aqueous sample solution (artificial pesticide contamination) by passing the sample through a composite product in the form layers containing Cg modified silica particles

-36gelu. In this case, the composite product contained 90% by weight of modified silica gel and 10% by weight of PTFE. The composite product was prepared by the intensive procedure described in Example 1 with an amount of lubricant (water / alcohol 1: 1) to Particles at 120%&gt; to give a mean pore size similar to Sample 2A (Λ *) (see Table 1).

Cut-out disk of material-layers of sample 2A of the example.

A diameter of 47 mm and a thickness of 0.5 mm was placed in a vacuum extraction apparatus described in Example 3 for the filtration (extraction stage).¹ The disk was first run in a 5 ml wash cycle. methanol and one liter of water with the addition of 5 ml of methanol. Both of these steps are necessary to wet the modified silica gel Οθ particles. Pesticides are preferably sorbed by hydrophobic particles and thus extracted / recovered from the water by passing it through a disk. The aqueous sample was forced through a disk using a vacuum. The amount of extracted pesticides was then identified and determined by first obtaining them from the composite product in

... very: · thickened. (50 DEG C.) and in pure form eluting with an organic liquid, i.e. ethyl acetate. The eluent was then subjected to gas chromatography analysis to determine the amount of pesticides isolated from the aqueous sample. The data (see Table 5) show that the composite layer was highly effective in trapping and isolating pesticides from water.

-3786

110

28^x

S6 responsible for the low composite product

Table 5

Percentage of obtaining pesticides in the amount of 1 ppb from surface water

---Pesticide--:------^:~ Propachlor ™ (Monsanto Co.)

TM

Atrazme (Geigy Agricultural Chemicals)

Metribuzin ™ · (Chemagro Agricultural Chemicals)

Alachior ™;

(Monsanto) Co.)

Cyanazme (Shell Chemical Co.)

Chlorpyrifos ™ (Dow Chemical) pesticide is suspected of degrading the yield value

Data in the table. 5 illustrate, according to the present invention, a solid phase extraction site on columns or cartridges can be used to isolate substances contaminating water, air, soil, food, beverages and the like and by correctly selecting sorption particles incorporated into the composite product and selecting solvent to obtain ( elution) of contaminants.

Disks, due to their large specific surface,. they allow faster flows at the same linear velocity of the particulate product than the cartridges allowed. The simple design of the discs, the inertness and the purity of the materials of the product result in a minimum of extractables by the elution liquid.

In some cases, contaminants were obtained from the product by heating the product and thermally desorbing the contaminants of interest, followed by analysis. Similarly, the contaminants could be recovered from the composite product using extraction with a supercritical fluid such as carbon dioxide, followed by analysis.

Example 5

Example 5 illustrates the use of polymer-coated inorganic particles instead of modified particles as a reverse phase for over-the-counter extraction of hydrophobic acid from water. The particles used in the example were 20 micrometer zirconia particles coated with 2% by weight of polybutadiene as disclosed in U.S. Patent No. 4,810,381, column 4, lines 33-65. The coated particles were incorporated into the composite product as described in Example 1. .

whose

The articles containing zirconia particles coated with carbon tetrachloride (in the form of titanium dioxide) are used to obtain &amp; concentrate the hydrophobic acid. contaminating the environment, from water in a manner similar to that described in Example 4 above. (dimethyl, diethyl, di-n-butyl and di-n-octyl), where the concentration of each compound was 100'ppb (micrograms per liter). Flow times for one liter of aqueous samples were 12 minutes, the eluent for the dye was methanol and for the phthalate esters (plasticizers) acetonitrile. After elution, the eluents were transferred to 10 ml volumetric flasks and analyzed by known procedures, visible spectrometry for dye determination (480 nanometers) and reverse phase high performance liquid chromatography for four phthalate esters. The analytical results are shown in the table below. 6. '

Table 6 variability, hydrophobic compounds using

Dispersion compound Red 1 dimethyl phthalate diethyl phthalate di-n-butyl phthalate di-n-octyl phthalate coated particles yield (percentage).

The data in Table 6 show that the disk containing the coated particles is suitable for obtaining hydrophobic compounds from substantially aqueous samples. Less hydrophobic compounds such as. dimethyl s. diethyl phthalate showed much lower yields.

Although the present invention has been demonstrated in the suitability of controlled pore size products for use in environmental and clinical scale separations and purifications in the laboratory, these applications can be extended to the operational range. These applications could include the treatment of air or water to remove contaminants or in the treatment of biological fluids for the purpose of recovering and isolating contaminants, e.g., certain toxins, metabolites, or drugs. ·

-40Example 6

'1' higher "temperatures can be used to make composite products. An example is a composite product comprising PTFE and silica gel (90: 100% by weight) produced at a calender roll temperature of 125 ° C. This product was prepared according to the procedure of Example 3, except that the amount of lubricant was 170% by weight of the particles. The sorption capacity of the silica gel particles for the lubricant was 140% by weight of the particles. Measured data showing the suitability of the obtained composite are given below in Table 7. "Filtration data were obtained from discs with an effective diameter of ~ 3'Smm.^-; ' ^;Table 7

Sample heat-% lubricant- size- TLC filtration No. ta ° C of the centrifuge (min / 50 (min / l) yum) 1)

ID 125 '170

0,61 -16.,00 ....._45,5.

The data in Table 7 show that 170% of the lubricant has a high temperature effect on its pore size.

i .over using the reduction of the middleExample '7'

The amount of PTFE in the product can be changed. In this example, a composite (disk ε with an effective diameter of 38 mm) was prepared according to the procedure of Example 3, except that the lubricant was used in a 3% weight excess relative to the sorption capacity of the lubricant particles (PTFE: silica gel was in weight ratio (80%: The mean pore size was too maldt to be measured with a Coulter Porometer (i.e., 20%).

-41 less than 0.2 micrometers). The results are shown in Table 8 below, Table 8

V yrT3c ~ e “: ΤΈ3 · _ -water (min / ml) -toluene / (min / ml) ____ (min / 50'mm)% PTFE, · 7.1 1.4 '42 0,

0 % silica gel. .

Example 8

A composite product (disc with an effective diameter of 38 mm) was produced from the material of Example 5 according to the procedure of Example 1, with a particle ratio (zirconia) of PTFE of 34: 1, and an amount of 30% by weight was used.

- lubricant with respect to the weight of the particles. The mean pore size was 2.45. This composite product filtered one liter of water in 4.23 minutes. These zirconia particles had a lubricant absorption capacity of about 25% by weight of the particles.

Various changes and modifications of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention, and it should be emphasized that the present invention is not limited to the following embodiments, which are to be construed as illustrative.