The invention relates to compositions and methods for the hydrophilisation of membranes, particularly hollow fibre membranes for use in microfiltration and ultrafiltration. The invention also relates to membranes prepared in accordance with these methods.
The following discussion is not to be construed as an admission with regard to the common general knowledge.
Synthetic membranes are used for a variety of applications including desalination, gas separation, filtration and dialysis. The properties of the membranes vary depending on the morphology of the membrane i.e. properties such as symmetry, pore shape and pore size and the polymeric material used to form the membrane.
Different membranes can be used for specific separation processes, including microfiltration, ultrafiltration and reverse osmosis. Microfiltration and ultrafiltration are pressure driven processes and are distinguished by the size of the particle or molecule that the membrane is capable of retaining or passing. Microfiltration can remove very fine colloidal particles in the micrometer and sub micrometer range. As a general rule, microfiltration can filter particles down to 0.1 μm, whereas ultrafiltration can retain particles as small as 0.01 μm and smaller. Reverse Osmosis operates on an even smaller scale.
As the size of the particles to be separated decreases, the pore size of the membrane must decrease and the pressure required to carry out the separation increases.
A large surface area is needed when a large filtrate flow is required. One known technique to make filtration apparatus more compact is to form a membrane in the shape of a hollow porous fibre. Modules of such fibres can be made with an extremely large surface area per unit volume.
Microporous synthetic membranes are particularly suitable for use in hollow fibres and are produced by phase inversion. In this process, at least one polymer is dissolved in an appropriate solvent and a suitable viscosity of the solution is achieved. The polymer solution can be cast as a film or hollow fibre, and then immersed in a precipitation bath such as water. This causes separation of the homogeneous polymer solution into a solid polymer and liquid solvent phase. The precipitated polymer forms a porous structure containing a network of uniform pores. Production parameters that affect the membrane structure and properties include the polymer concentration, the precipitation media and temperature and the amount of solvent and non-solvent in the polymer solution. These factors can be varied to produce microporous membranes with a large range of pore sizes (from less than 0.1 to 20 μm), and altering chemical, thermal and mechanical properties.
Microporous phase inversion membranes are particularly well suited to the application of removal of viruses and bacteria. Of all types of membranes, the hollow fibre contains the largest membrane area per unit volume.
Flat sheet membranes are prepared by bringing a polymer solution consisting of at least one polymer and solvent into contact with a coagulation bath. The solvent diffuses outwards into the coagulation bath and the precipitating solution will diffuse into the cast film. After a given period of time, the exchange of the non-solvent and solvent has proceeded such that the solution becomes thermodynamically unstable and de-mixing occurs. Finally a flat sheet is obtained with an asymmetric or symmetric structure.
Hydrophobic surfaces are defined as “water hating” and hydrophilic surfaces as “water loving”. Many of the polymers used in the manufacture of porous membranes are hydrophobic polymers. Water can be forced through a hydrophobic membrane, but usually only under very high pressure (150-300 psi). Membranes may be damaged at such pressures and under these circumstances generally do not become wetted evenly.
Hydrophobic microporous membranes are characterised by their excellent chemical resistance, biocompatibility, low swelling and good separation performance. Thus, when used in water filtration applications, hydrophobic membranes need to be hydrophilised or “wet out” to allow water permeation. Some hydrophilic materials are not suitable for microfiltration and ultrafiltration membranes that require mechanical strength and thermal stability since water molecules present in the polymer can play the role of plasticizers.
Currently, poly(tetrafluoroethylene) (PTFE), Polyethylene (PE), Polypropylene (PP) and poly(vinylidene fluoride) (PVDF) are the most popular and available hydrophobic membrane materials. Poly(ethylene-chlorotrifluoroethylene) sold under the trademark HALAR is another hydrophobic material showing promise as a membrane polymeric material.
Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer containing a crystalline phase and an amorphous phase. The crystalline phase provides good thermal stability whilst the amorphous phase adds some flexibility to the membrane. PVDF exhibits a number of desirable characteristics for membrane applications, including thermal resistance, reasonable chemical resistance (to a range of corrosive chemicals, including sodium hypochlorite), and weather (UV) resistance.
While PVDF has to date proven to be one of the most desirable options from among those materials suitable for microporous membranes, the search continues for membrane materials which will provide better chemical stability and performance while retaining the desired physical properties required to allow the membranes to be formed and worked in an appropriate manner.
Given the good membrane forming properties of hydrophobic membranes and their favourable mechanical and chemical properties, as well as the general familiarity in the industry with such materials, one approach to hydrophilic membranes is to synthesise membranes based around a hydrophobic polymer but with modification of the hydrophobic/hydrophilic balance of the membrane. The two main modes of modifying membrane property are (i) to modify the starting materials, reagents or conditions used to produce the membrane or (ii) to modify the membrane after production (post-treatment). Combinations of the two approaches are also possible, for example, introducing components into a membrane which alone may not alter membrane function, but which do interact with reagents subsequently applied to produce a membrane with a modified property.
The present applicants have found that, in certain cases. Poly(VinylMethylEther) (PVME) can be used to modify, and in particular, reduce, the hydrophobicity of certain hydrophobic membranes. The PVME can be incorporated either by means of post-treatment, such as by soaking hollow-fibre membranes in a solution of PVME, or by incorporating PVME into the dope solution for forming the membrane. Either approach could be demonstrated for a variety of reaction types, including different types of membranes such as Poly(vinylidene fluoride) (PVDF). Poly(ethylene-chlorotrifluoroethylene) sold under the trademark HALAR and Poly(propylene) (PP).
PVME as a post-treatment was found to make PVDF and Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes hydrophilic, although the treatment was also useful on PP membranes.
PVME as a membrane additive was found to induce variations in the pore structure of PVDF such as asymmetry, as well as to impart hydrophilicity to the final membrane. This was apparent for both TIPS and DIPS methods of making a membrane.
As used herein. PVME also encompasses not only the polymeric form of the product, but also the monomeric form of the compound, namely vinylmethyl ether, as well as di-, tri-, and oligomeric forms.
According to a first aspect, the invention provides a polymeric ultra or microfiltration membrane incorporating PVME. The polymeric ultra or microfiltration membrane may incorporate a coating of PVME or, alternatively include a homogeneous dispersion of PVME throughout the polymer or both.
The polymeric membrane may include a heterogeneous dispersion of PVME throughout the polymer.
In another aspect, the invention provides a hydrophilic polymeric membrane including one or more of Poly(ethylene-chlorotrifluoroethylene) sold under the trademark HALAR, PVDF or PP.
In yet another aspect, the invention provides a hydrophilic polymeric membrane having a highly asymmetric structure, preferably formed from one or more of Poly(ethylene-chlorotrifluoroethylene) sold under the trademark HALAR, PVDF or PP.
Preferably the membrane has a reduced pore size as a result of the addition of PVME. Preferably also, the membrane is substantially free from macrovoids.
Preferably, the membrane according to the present invention contains cross linked PVME. The membrane according to the present invention may incorporate adsorbed PVME and embedded PVME and wherein adsorbed PVME is cross-linked with embedded PVME.
Preferably the polymeric ultra or microfiltration membranes of the present invention contain PVDF and PVME in a ratio of 0.1:24 to 0.5 to 24, more preferably in a ratio of 0.5:18 to 1:18 and even more preferably in a ratio of 0.4:13 to 2.3:13.
The polymeric ultra or microfiltration membranes preferably contain 0.4 to 30 with % PVME.
In one embodiment, polymeric ultra or microfiltration membranes of the present invention on soaking for 8 hours produce a detectable quantity of PVME, or for example, on soaking for 48 hours produces a leachate having at least 5 ppm PVME.
Preferably the hydrophobic polymeric ultra or microfiltration membranes are rendered hydrophilic by contacting the membrane with an aqueous or alcoholic solution of PVME with a concentration 0.05 to 5 wt %. More preferably, the polymeric ultra or microfiltration membranes are rendered hydrophilic by contacting the membrane with an aqueous or alcoholic solution of PVME with a concentration of 0.05 to 5 wt %, at a pressure of 0.5 to 50 bar.
According to a second aspect, the invention provides a method of hydrophilising a membrane prepared from a polymeric material, said method including the step of contacting said polymeric material with a compatible at least partially water soluble polymeric hydrophilising agent.
Preferably, the at least partially water soluble polymeric hydrophilising agent is soluble in an amount of at least 5-10 g/l at standard temperature and pressure.
Preferably, the at least partially water soluble polymeric hydrophilising agent contains vinylmethyl ether monomers. More preferably, the polymeric hydrophilising agent is polyvinylmethyl ether (PVME).
The polymeric hydrophilising agent may be a copolymer containing vinylmethyl ether monomer and at least one other co-monomer. It is preferred that the vinylmethyl ether monomer is present in an amount of at least 50 mole % of the polymeric hydrophilising agent.
If a co monomer is used, it is preferred if the co-monomer is selected from the group consisting of: co-polymerisable acrylate monomers and co-polymerisable vinyl monomers.
More preferably, the co-monomer is selected from the group consisting of: vinyl acetate, acrylic acid, methyl acrylate, methyl methacrylate, allyl methacrylate, ethyl acrylate, ethyl methacrylate, methacrylic acid, fumaric acid, monoesters of fumaric acid, diesters of fumaric acid, maleic acid, monoesters of maleic acid, diesters maleic acid, diallyl maleate maleic anhydride, esters of adipic acid (divinyl adipate), ethylenically unsaturated carboxamides (acrylamide), ethylenically unsaturated carbo-nitriles (acrylonitrile), ethylenically unsaturated sulfonic acids (vinylsulfonic acid).
According to a third aspect the invention provides a method of modifying the hydrophobic/hydrophilic balance of a polymer membrane prepared from a polymeric material, said method including the step of contacting said polymeric material with polyvinylmethyl ether (PVME) to produce a modified polymeric membrane.
Preferably the polymeric membrane is coated with PVME.
The membrane may be in the form of an ultrafiltration membrane or a microfiltration membrane
In one preferred embodiment, the polymeric material is a hydrophobic polymer and hydrophobic/hydrophilic balance of the polymer is modified to provide a hydrophilic modified polymeric membrane.
For preference, the polymeric material is poly(vinylidene fluoride) (PVDF), poly(ethylene-chlorotrifluoroethylene) sold under the trademark HALAR and poly(propylene) (PP) or mixtures thereof. Poly(vinylidene fluoride) (PVDF) and poly(ethylene-chlorotrifluoroethylene) sold under the trademark HALAR are particularly preferred.
The polymeric material may be a formed membrane treated with a solution of PVME. Preferably, the polymeric material is treated with a solution of PVME at a concentration and for a time sufficient to allow PVME saturation of said membrane to take place. In one preferred embodiment, the polymeric material is post treated by soaking in a solution of PVME in ethanol. In another preferred embodiment, the polymeric material is post treated by soaking in a solution of PVME in water
It is preferred that the concentration of PVME is less than 10%, more preferably less than 5% and even more preferably less than 3%, however it is preferred that the concentration of PVME is greater then 0.1%.
A range of 1 to 5% is particularly preferred.
It is preferred that treatment with PVME takes place for between 5 minutes and 16 hours. Preferably, such treatment with a solution of PVME is followed by a rinsing stage to remove unbound PVME.
In an alternative embodiment, the polymeric material is treated with PVME by means of adding PVME to a membrane dope prior to casting. The membrane dope may be cast via a thermally induced phase separation process or by a diffusion induced phase separation process.
Preferably, the membrane dope includes PVME in an amount up to 1 wt % when a TIPS process is employed, or higher if a DIPS process is used. Preferably, the PVME is dissolved in a polymer dope/solvent/non-solvent mixture. More preferably, the solvent/non-solvent mixture includes a PVME solvent and PVME non-solvent
Preferably, the PVME solvent possesses weak polarity, for example, glyceroltriacteate. Preferably, the PVME non-solvent is strongly polar, for example, diethylene glycol, triethylene glycol, 1,4-butanediol or mixtures thereof.
Preferably, the solvent mixture includes from 40-60% non-solvent.
Preferably, the solvent mixture includes PVME in an amount of 0.1-2 wt %, and more preferably in an amount of 0.7-1 wt %.
Preferably, when the method of casting is a TIPS process, it further includes treatment with a coating solution which most preferably contains a solvent and a non-solvent. When a DIPS process is used, it is preferred that N-methylpyrrolidone is present as a solvent, and water is present as non-solvent.
The present invention also provides a method wherein PVME is incorporated in the membrane dope and formed into a membrane, and wherein said membrane is further treated with PVME, for example the membrane is treated to cross-link incorporated and adsorbed PVME. A preferred method of cross linking is e-beam irradiation.
PVME readily cross-links upon irradiation with electron beams or γ-radiation and is of very low toxicity, as are the starting vinyl methyl ether monomer and its degradation products. This makes it a suitable candidate for many applications requiring biocompatibility. Further, despite already possessing a low toxicity, the starting vinyl ether monomer is readily hydrolysed at pH 7 or below and so can be readily removed, reducing even further any risk of membrane contamination by residual monomer.
PVME was surprisingly found to be effective at hydrophilising otherwise hydrophobic PP, PVDF and Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes either by soaking the membrane as a post treatment or by including the PVME as a hydrophilising agent incorporated in the membrane dope. Hydrophilisation can be achieved either by soaking the membranes in a solution of PVME in a suitable solvent, for example, ethanol or water, preferably at a level greater than 0.5 wt %. PVDF and Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes in particular demonstrate long term stability with PVME adsorbed onto the surface, although PVME also appears to have good affinity with PP. Leaching tests show minimal leaching of PVME from the membranes after 10 days with the PVDF and Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) samples are all still hydrophilic after this period of time.
Including PVME into the dope via a TIPS process was also successful in imparting hydrophilicity to the membranes. The proportion of PVME in the dope was most preferably between 0.1 and 0.5%, although this is dependent upon the amount of non-solvent in the dope. If the proportion of non-solvent used was lower than 60 wt % a larger amount of PVME could be incorporated into the dope. Surprisingly, it was found that the introduction of PVME into membrane dope induced structural changes in the membranes, such as increased asymmetry and smaller pores in addition to imparting hydrophilicity to the membrane.
PVME could also be successfully incorporated into the dope via a DIPS process. As well as modifying the hydrophilic/hydrophobic balance, the presence of PVME significantly altered the base PVDF membrane structure and suppressed the formation of macrovoids. In the case of the DIPS process, it was found desirable to employ higher concentrations of PVDF as well as higher concentrations of PVME to achieve a high permeability membrane with good virus/dextran retention.
PVME modified membranes can be further modified, for example, by irradiation with electrons (e-beam). PVME is cross-linkable and under irradiation will cross-link on the membrane surface. Irradiation can be applied either to membranes that have been post-treated in PVME or to membranes that have had PVME included in the dope. PVME may, under appropriate conditions, also cross-link with PVDF when this is present in the membrane matrix.
PVDF and fluoropolymers with a similar structure (e.g. PVC, PVF, and PVDC) are known to undergo some cross-linking upon irradiation with electrons or γ-radiation and similar crosslinking with PVME is also possible. Those skilled in the art will appreciate that when y-radiation is used on fluoropolymers, caution must be taken because there is possibility of chain scission (degradation).
Membranes with a cross-linkable hydrophilising agent in the dope may also be post-treated with additional cross-linkable agent (which may be the same or different to that used in the dope) and subsequently exposed to e-beam. This allows the adsorbed crosslinkable agent to cross-link with the embedded PVME agent, reducing the opportunity for the former to be desorbed from the surface.
A specific example of this is the preparation of membranes incorporating PVME in the dope which are also be post-treated with an aqueous PVME solution and subsequently exposed to e-beam irradiation. Without wishing to be bound by theory, it is believed that this allows adsorbed PVME to cross-link with embedded PVME and be anchored to the surface of the membrane, reducing the opportunity for the PVME to be desorbed from the surface and dissolve into solution.
The post-treatment of a variety of membranes with a cross-linkable hydrophilising agent was investigated, PVDF, Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) and PP membranes were all tested. For the Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes, both MF (microfiltration) and UF (ultrafiltration) membranes were tested.
The general procedure for treating the pre-prepared PP and PVDF membranes was as follows:
The dry membrane was soaked in a PVME (Lutonal M40) solution with, solvent, concentration and soaking time as specified. The membrane was subsequently removed from the PVME solution and placed into wash water for 4 hrs. The membrane was then dried for about 4 hrs
The membrane was then tested for the ‘wicking’ of an aqueous solution of dye and the permeability of the fibre was also tested.
A sample of the membrane was then soaked in water at 65° C. for 1 hr and the permeability of the heat-treated membrane was also tested.
The general procedure for treating the pre-prepared Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes was more elaborate due to glycerol-loaded pores which are present as a result of the method of production of Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes. The membrane was soaked in ethanol for 12 hrs, followed by water for 15 minutes.
The membrane was then soaked in a PVME (Lutonal M40) solution with, solvent, concentration and soaking time as specified. The membrane was subsequently removed from the PVME solution and placed into wash water for 4 hrs. The membrane was then dried for about 4 hrs before being resoaked in an aqueous solution of 20 wt % glycerol for 16 hr to reload the pores. The membrane was then dried for 24 hr and the permeability of the standard untreated and treated membranes was tested.
All fibres were treated as described, with various concentrations of PVME and for varying lengths of time. Tables 1-3 below give the results from each variation of each fibre tested.
Wicking is said to have occurred if a solution of dye is spontaneously absorbed into a fibre that is partially submerged vertically in such a solution and travels upwards above the solution meniscus. This can clearly be seen in strongly hydrophilic fibres (capillary action) but not in hydrophobic fibres. Wicking tests were not conducted with the Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) fibres, as an artificial result would arise as a result of the glycerol in the pores.
The results in Table 1 demonstrate that PVDF is made hydrophilic by PVME post-treatment. Different concentrations of PVME (0-3 wt %) in water or in ethanol were investigated. The concentration of PVME in solution appears unimportant provided it is above a certain critical value, which is believed to be about 0.1%. There would appear to be little benefit in using more than 0.5% PVME. It is pox postulated that this may be dependent upon the fibre density in the solution, or in other words the ratio of available membrane surface area to free solution, since if PVME is adsorbing to the membrane surface there is a minimum PVME quantity in solution required to obtain a totally hydrophilic membrane surface. There will simply be no room on the membrane surface for any excess PVME to adsorb and as a consequence will be washed out of the membrane upon filtration.
If too little PVME is added, the surface may not be completely hydrophilic which may in turn affect complexing and linking.
The results in Table 2 show that PP can be made hydrophilic as demonstrated by wicking (see column 2 of Table 2) but the permeability is only about half that of the standard untreated PP membrane fibre.
It appears from these results that the interaction of PP with PVME is not the same as the interaction between PVDF and PVME. Without wishing to be bound by theory, it is postulated that the PVME is more strongly attracted to the PVDF surface that is slightly polar, rather than the PP surface which may be considered entirely non-polar. It seems that this affinity may be the effect that is dominating rather than that PVME is simply attracted to a hydrophobic surface in preference over solution in water.
The permeability of Halar Poly(ethylene-chlorotrifluoroethylene) sold under the trademark HALAR is slightly reduced as a result of PVME treatment. Generally permeability measurements for Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) MF fibre range between 1500-2000 LMH/bar, with Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) UF membranes varying between 200-600 LMH/bar.
The results from the Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes are difficult to quantify with precision because it is believed that glycerol in the pores results in lower initial clean water permeabilities that slowly increase towards a fixed value as the glycerol is completely removed from the pores. This may explain why the ethanol washed fibres have a slightly higher apparent permeability, since glycerol is more readily soluble in ethanol than in water.
Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) has a mildly polar structure not dissimilar to PVDF and the affinity between HALAR and PVME replicate to a degree the interaction between PVME and PVDF. The results below give an indication of the permanency of the treatment of Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) membranes with PVME.
Wicking can clearly be seen in strongly hydrophilic fibres (capillary action) but not in hydrophobic fibres.
The leaching tests (
Leaching tests were conducted by soaking the fibres in reverse osmosis (RO) water for 240 hrs. The leach water was refreshed every 24 hours (the wash water being replaced a total of 9 times) and an aliquot was analysed by UV-Vis absorption and compared against a PVME calibration curve. The results above show that there is an immediate decline in the detection of PVME which this occurs for both wet and dry standards as well as for all samples. The biggest decline comes from the samples soaked in PVME, while of these samples the fibres soaked in 1 wt % ethanolic PVME have the lowest starting concentration. The general trend appears to be that some MIME leaches out immediately but after approximately 48 hrs there is no significant change in the PVME level in the wash water compared to the standard. As described above however, the change in the concentration cannot be considered significant compared to the standards on the basis of this examination.
The dry standard appears at first to increase in PVME concentration initially, to a concentration that is above the sample soaked in 1 wt % ethanolic PVME and the Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) sample.
An ethanol-wet standard and a dry standard were both used because there can be very small quantities of residual solvent in the PVDF membranes that are only slightly soluble in water and although very difficult to leach out entirely would nevertheless affect the UV-Vis readings. Washing with ethanol prior to UV-Vis analysis should remove any residual solvent from the membrane. This may explain why the PVDF samples appear to rise in PVME leach concentration or have a slightly higher steady-state value rather than the ethanol-wet sample. However, it is also possible that the PVME may bind more firmly to the Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) surface rather than the PVDF surface, from an aqueous solution.
The permeabilities of a number of membranes before and after PVME treatment are shown in Table 4.
In order to test the permeability after leaching, the fibres were removed from the RO water and dried at room temperature. The standard (non-treated) fibres were wet with ethanol prior to testing the permeability, while the treated fibres were simply tested with water. The results for permeability show that the fibres are still hydrophilic after this period of leaching, but that the permeabilities have dropped noticeably. This is a relatively uniform drop however and is between 40-55% across all samples including the standards, with the exception of the samples soaked in 1 wt % aqueous PVME.
aSince the dry blank was NOT to be treated with ethanol (including wetting out), it was assumed that the permeabilities for the two standard samples are identical, since they are obtained from the same source.
Soaking PVDF fibre membranes in PVME did not appear to modify the mechanical properties of any of the samples in any way. Treated membranes demonstrated the same break extensions as untreated samples.
Dope Addition Studies
TIPS Membranes
PVME was added to standard TIPS PVDF or TIPS Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR) dope in proportions varying from 0 to 1 wt %. The TIPS extrusion was operated in a continuous process (although there is nothing to prohibit its use in batch processes if desired). For PVDF, PVME was dissolved into the solvent/non-solvent mixture of GTA and diethylene glycol, triethylene glycol or 1,4-butanediol. For Poly(ethylene-chlorotrifluoroethylene) (sold under the trademark HALAR), PVME was simply dissolved in GTA. PVME is highly soluble in GTA but insoluble in more polar compounds like diethylene glycol, triethylene glycol and 1,4-butanediol.
Because this mixture was between 40-60 wt % non-solvent, there was a maximum amount of PVME that could be dissolved into the solvent/non-solvent mixture (approx. 0.7 wt %). However, membranes formed with this proportion of PVME gave SEMs that suggested some de-mixing of PVDF was occurring. Thus, in most circumstances, it is envisaged that a sub-saturation level of PVME was required.
Membranes were prepared with concentrations as a proportion of the dope mixture of 0.1-0.2 wt % and their properties tested. There was no indication from any of the experiments of any thermal instability of PVME during extrusion of the membranes. Table 5 below shows the details of the different TIPS membranes.
The differences between the structures of the membranes, as observed by SEM for the samples with and without PVME are only minor for 0.1 and 0.2 wt %. These can be seen in
However such a high proportion of PVME does not appear to be necessary to impart hydrophilicity to the fibres. 0.1 wt % appears sufficient to commence hydrophilising the membrane, but at this level there appears to be some portions of the fibres that were not hydrophilic; that is to say that upon immersion in water only sections of the fibre could be seen to wet out, while some sections remained dry, but would wet with the assistance of ethanol. However, with 0.2 wt % PVME present in the fibre complete hydrophilisation appeared to have taken place.
It is also noted that higher proportions of PVME in the membrane appear to cause a greater degree of asymmetry, which up to a point is a desirable property in MF and IF membranes. Although the samples with 0.5 and 1 wt % PVME show evidence of de-mixing as discussed earlier, they also show a high degree of asymmetry which can be attributed directly to the PVME in the structure. In addition this de-mixing can be used to induce small pores by working as a nucleating agent and encouraging phase separation. The relationship between asymmetry and PVME content is demonstrated by the trend toward increasing bubble point as the PVME content increases.
In summary, incorporating PVME into the dope in TIPS trials was successful in imparting hydrophilicity to the membranes. The proportion of PVME used was most preferably between 0.1 and 0.5%, although this is dependent upon the amount of non solvent in the dope. If the proportion of non solvent used was lower than 60 wt %, a larger amount of PVME could be incorporated into the dope. However, the preferred range recited above is sufficient in most cases to begin to induce structural changes in the membrane such as asymmetry and smaller pores, as well as cause the membrane to be hydrophilic.
DIPS Membranes
Three dopes were prepared with the compositions listed in Table 6 below. Two different proportions of PVME a 1 wt % and 2.5 wt %) were compared with a DIPS PVDF dope that contained poly(vinylpyrrolidone-vinylacetate) (S630) as an alternative additive. These fibres were all extruded in an identical manner and the results are compared below.
The fibres show an increase in break extension, break force and bubble point by when PVME was added. Without wishing to be bound by theory, these increases may be partly due to a viscosity effect in that replacing S630 with PVME results in a more viscous dope which may in turn lead to fewer macrovoids and a more robust structure, giving a higher break force and break extension, and also possibly contributing to the increase in bubble point. The variation in permeability is possibly due to the change in water (non-solvent) concentration between the samples.
The SEMs in
All samples wicked water quite thoroughly, and there was no difference observed from the hydrophilicity of the standard formulation. The permeability measurements were conducted without a ‘wetting’ step—a manual wetting out of the membrane with ethanol. The permeability of 2.3 wt % PVME samples appears to increase over 0.4 wt % PVME samples. Since the bubble point is the same for these two samples while permeability varies, it can be seen that increasing the PVDF concentration and adding different PVME concentrations allow a UF membrane with a high permeability to be produced.
Number | Date | Country | Kind |
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2003903507 | Jul 2003 | AU | national |
This application is a continuation of and claims priority to U.S. nonprovisional patent application Ser. No. 10/564,024 filed on Jan. 9, 2006, issued as U.S. Pat. No. 7,662,212 B2 on Feb. 16, 2010 titled MEMBRANE POST TREATMENT which is a U.S. national stage application and claims the benefit under 35 U.S.C. §371 of International Application No. PCT/AU2004/000922 filed on Jul. 8, 2004, entitled titled MEMBRANE POST TREATMENT, which is based on Australian Patent Application No. 2003903507 filed on Jul. 8, 2003, entitled MEMBRANE POST TREATMENT, each of which is entirely incorporated herein by reference for all purposes, and to which this application claims the benefit of priority.
Number | Name | Date | Kind |
---|---|---|---|
1994135 | Horowitz | Mar 1935 | A |
2658045 | Schildknecht | Nov 1953 | A |
3228876 | Mahon | Jan 1966 | A |
3275554 | Wagenaar | Sep 1966 | A |
3373056 | Martin | Mar 1968 | A |
3556305 | Shorr | Jan 1971 | A |
3625827 | Wildi et al. | Dec 1971 | A |
3654147 | Levin | Apr 1972 | A |
3693406 | Tobin, III | Sep 1972 | A |
3708071 | Crowley | Jan 1973 | A |
3728256 | Cooper | Apr 1973 | A |
3864289 | Rendall | Feb 1975 | A |
3876738 | Marinaccio et al. | Apr 1975 | A |
3968192 | Hoffman, III et al. | Jul 1976 | A |
3992301 | Shippey et al. | Nov 1976 | A |
3993816 | Baudet et al. | Nov 1976 | A |
4033817 | Gregor | Jul 1977 | A |
4142526 | Zaffaroni et al. | Mar 1979 | A |
4188817 | Steigelmann | Feb 1980 | A |
4192750 | Elfes et al. | Mar 1980 | A |
4193780 | Cotton, Jr. et al. | Mar 1980 | A |
4203848 | Grandine, II | May 1980 | A |
4218324 | Hartmann et al. | Aug 1980 | A |
4230583 | Chiolle et al. | Oct 1980 | A |
4247498 | Castro | Jan 1981 | A |
4248648 | Kopp | Feb 1981 | A |
4253936 | Leysen et al. | Mar 1981 | A |
4302336 | Kawaguchi et al. | Nov 1981 | A |
4340479 | Pall | Jul 1982 | A |
4353802 | Hara et al. | Oct 1982 | A |
4354443 | Abrahamson | Oct 1982 | A |
4384474 | Kowalski | May 1983 | A |
4385150 | Miyake et al. | May 1983 | A |
4388189 | Kawaguchi et al. | Jun 1983 | A |
4407975 | Yamaguchi | Oct 1983 | A |
4431545 | Pall et al. | Feb 1984 | A |
4439217 | Yamabe et al. | Mar 1984 | A |
4451369 | Sekino et al. | May 1984 | A |
4511471 | Muller | Apr 1985 | A |
4519909 | Castro | May 1985 | A |
4540490 | Shibata et al. | Sep 1985 | A |
4547289 | Okano et al. | Oct 1985 | A |
4559139 | Uemura et al. | Dec 1985 | A |
4609465 | Miller | Sep 1986 | A |
4614109 | Hofmann | Sep 1986 | A |
4618533 | Steuck | Oct 1986 | A |
4623670 | Mutoh et al. | Nov 1986 | A |
4623690 | Patzschke et al. | Nov 1986 | A |
4629563 | Wrasidlo | Dec 1986 | A |
4632745 | Giuffrida et al. | Dec 1986 | A |
4636296 | Kunz | Jan 1987 | A |
4642182 | Drori | Feb 1987 | A |
4647377 | Miura | Mar 1987 | A |
4650586 | Ellis, III | Mar 1987 | A |
4656865 | Callan | Apr 1987 | A |
4660411 | Reid | Apr 1987 | A |
4670145 | Edwards | Jun 1987 | A |
4673507 | Brown | Jun 1987 | A |
4687561 | Kunz | Aug 1987 | A |
4688511 | Gerlach et al. | Aug 1987 | A |
4695592 | Itoh et al. | Sep 1987 | A |
4702836 | Mutoh et al. | Oct 1987 | A |
4702840 | Degen et al. | Oct 1987 | A |
4707266 | Degen et al. | Nov 1987 | A |
4708799 | Gerlach et al. | Nov 1987 | A |
4718270 | Storr | Jan 1988 | A |
4744240 | Reichelt | May 1988 | A |
4756875 | Tajima et al. | Jul 1988 | A |
4758251 | Swedo et al. | Jul 1988 | A |
4763612 | Iwanami | Aug 1988 | A |
4767539 | Ford | Aug 1988 | A |
4775471 | Nagai et al. | Oct 1988 | A |
4779448 | Gogins | Oct 1988 | A |
4784771 | Wathen et al. | Nov 1988 | A |
4793932 | Ford et al. | Dec 1988 | A |
4797187 | Davis et al. | Jan 1989 | A |
4797211 | Ehrfeld et al. | Jan 1989 | A |
4810384 | Fabre | Mar 1989 | A |
4812235 | Seleman et al. | Mar 1989 | A |
4816160 | Ford et al. | Mar 1989 | A |
4840227 | Schmidt | Jun 1989 | A |
4846970 | Bertelsen et al. | Jul 1989 | A |
4855163 | Joffee et al. | Aug 1989 | A |
4876006 | Ohkubo et al. | Oct 1989 | A |
4876012 | Kopp et al. | Oct 1989 | A |
4886601 | Iwatsuka et al. | Dec 1989 | A |
4886668 | Haslam et al. | Dec 1989 | A |
4888115 | Marinaccio et al. | Dec 1989 | A |
4892739 | Shah et al. | Jan 1990 | A |
4904426 | Lundgard et al. | Feb 1990 | A |
4909943 | Fibiger et al. | Mar 1990 | A |
4921610 | Ford et al. | May 1990 | A |
4931186 | Ford et al. | Jun 1990 | A |
4935143 | Kopp et al. | Jun 1990 | A |
4963304 | Im et al. | Oct 1990 | A |
4968733 | Muller et al. | Nov 1990 | A |
4999038 | Lundberg | Mar 1991 | A |
5005430 | Kibler et al. | Apr 1991 | A |
5015275 | Beck et al. | May 1991 | A |
5017292 | DiLeo et al. | May 1991 | A |
5019260 | Gsell et al. | May 1991 | A |
5024762 | Ford et al. | Jun 1991 | A |
5032282 | Linder et al. | Jul 1991 | A |
5043113 | Kafchinski et al. | Aug 1991 | A |
5049275 | Gillberg-LaForce et al. | Sep 1991 | A |
5066375 | Parsi et al. | Nov 1991 | A |
5066401 | Muller et al. | Nov 1991 | A |
5066402 | Anselme et al. | Nov 1991 | A |
5069065 | Sprunt et al. | Dec 1991 | A |
5075065 | Effenberger et al. | Dec 1991 | A |
5076925 | Roesink et al. | Dec 1991 | A |
5079272 | Allegrezza, Jr. et al. | Jan 1992 | A |
5094750 | Kopp et al. | Mar 1992 | A |
5104535 | Cote et al. | Apr 1992 | A |
5104546 | Filson et al. | Apr 1992 | A |
H001045 | Wilson | May 1992 | H |
5135663 | Newberth, III et al. | Aug 1992 | A |
5137631 | Eckman et al. | Aug 1992 | A |
5137633 | Wang | Aug 1992 | A |
5138870 | Lyssy | Aug 1992 | A |
5147553 | Waite | Sep 1992 | A |
5151191 | Sunaoka et al. | Sep 1992 | A |
5151193 | Grobe et al. | Sep 1992 | A |
5158721 | Allegrezza, Jr. et al. | Oct 1992 | A |
5182019 | Cote et al. | Jan 1993 | A |
5192456 | Ishida et al. | Mar 1993 | A |
5192478 | Caskey | Mar 1993 | A |
5194149 | Selbie et al. | Mar 1993 | A |
5198116 | Comstock et al. | Mar 1993 | A |
5198162 | Park et al. | Mar 1993 | A |
5209852 | Sunaoka et al. | May 1993 | A |
5211823 | Giuffrida et al. | May 1993 | A |
5221478 | Dhingra et al. | Jun 1993 | A |
5227063 | Langerak et al. | Jul 1993 | A |
5248424 | Cote et al. | Sep 1993 | A |
5275766 | Gadkaree et al. | Jan 1994 | A |
5286324 | Kawai et al. | Feb 1994 | A |
5288324 | Shaneyfelt | Feb 1994 | A |
5297420 | Gilliland et al. | Mar 1994 | A |
5320760 | Freund et al. | Jun 1994 | A |
5353630 | Soda et al. | Oct 1994 | A |
5354587 | Abayasekara | Oct 1994 | A |
5361625 | Ylvisaker | Nov 1994 | A |
5364527 | Zimmermann et al. | Nov 1994 | A |
5376274 | Muller et al. | Dec 1994 | A |
5389260 | Hemp et al. | Feb 1995 | A |
5396019 | Sartori et al. | Mar 1995 | A |
5401401 | Hickok et al. | Mar 1995 | A |
5403479 | Smith et al. | Apr 1995 | A |
5403483 | Hayashida et al. | Apr 1995 | A |
5405528 | Selbie et al. | Apr 1995 | A |
5411663 | Johnson | May 1995 | A |
5417101 | Weich | May 1995 | A |
5419816 | Sampson et al. | May 1995 | A |
5451317 | Ishida et al. | Sep 1995 | A |
5470469 | Eckman | Nov 1995 | A |
5477731 | Mouton | Dec 1995 | A |
5480553 | Yamamori et al. | Jan 1996 | A |
5491023 | Tsai et al. | Feb 1996 | A |
5525220 | Yagi et al. | Jun 1996 | A |
5531848 | Brinda et al. | Jul 1996 | A |
5531900 | Raghavan et al. | Jul 1996 | A |
5543002 | Brinda et al. | Aug 1996 | A |
5543465 | Bell et al. | Aug 1996 | A |
5547575 | Demmer et al. | Aug 1996 | A |
5554283 | Brinda et al. | Sep 1996 | A |
5607593 | Cote et al. | Mar 1997 | A |
5629084 | Moya | May 1997 | A |
5639373 | Mahendran et al. | Jun 1997 | A |
5643455 | Kopp et al. | Jul 1997 | A |
5647988 | Kawanishi et al. | Jul 1997 | A |
5725769 | Miller et al. | Mar 1998 | A |
5747605 | Breant et al. | May 1998 | A |
D396046 | Scheel et al. | Jul 1998 | S |
D396477 | Sadr | Jul 1998 | S |
5783083 | Henshaw et al. | Jul 1998 | A |
D400890 | Gambardella | Nov 1998 | S |
5871823 | Anders et al. | Feb 1999 | A |
5906742 | Wang et al. | May 1999 | A |
5910250 | Mahendran et al. | Jun 1999 | A |
5914039 | Mahendran et al. | Jun 1999 | A |
5918264 | Drummond et al. | Jun 1999 | A |
5942113 | Morimura | Aug 1999 | A |
5944997 | Pedersen et al. | Aug 1999 | A |
5958243 | Lawrence et al. | Sep 1999 | A |
5981614 | Adiletta | Nov 1999 | A |
5988400 | Karachevtcev et al. | Nov 1999 | A |
6024872 | Mahendran et al. | Feb 2000 | A |
6039872 | Wu et al. | Mar 2000 | A |
6042677 | Mahendran et al. | Mar 2000 | A |
6045698 | Cote et al. | Apr 2000 | A |
6045899 | Wang et al. | Apr 2000 | A |
6048454 | Jenkins | Apr 2000 | A |
6056903 | Greenwood et al. | May 2000 | A |
6074718 | Puglia et al. | Jun 2000 | A |
6077435 | Beck et al. | Jun 2000 | A |
6083393 | Wu et al. | Jul 2000 | A |
6096213 | Radovanovic et al. | Aug 2000 | A |
6113794 | Kumar et al. | Sep 2000 | A |
6146747 | Wang et al. | Nov 2000 | A |
6156200 | Zha et al. | Dec 2000 | A |
6159373 | Beck et al. | Dec 2000 | A |
6193890 | Pedersen et al. | Feb 2001 | B1 |
6202475 | Selbie et al. | Mar 2001 | B1 |
6214231 | Cote et al. | Apr 2001 | B1 |
6221247 | Nemser et al. | Apr 2001 | B1 |
6245239 | Cote et al. | Jun 2001 | B1 |
6254773 | Biltoft | Jul 2001 | B1 |
6264839 | Mohr et al. | Jul 2001 | B1 |
6277512 | Hamrock et al. | Aug 2001 | B1 |
6280626 | Miyashita et al. | Aug 2001 | B1 |
6284135 | Ookata | Sep 2001 | B1 |
6294039 | Mahendran et al. | Sep 2001 | B1 |
6299773 | Takamura et al. | Oct 2001 | B1 |
6315895 | Summerton et al. | Nov 2001 | B1 |
6322703 | Taniguchi et al. | Nov 2001 | B1 |
6325928 | Pedersen et al. | Dec 2001 | B1 |
6337018 | Mickols | Jan 2002 | B1 |
RE037549 | Mahendran et al. | Feb 2002 | E |
6354444 | Mahendran et al. | Mar 2002 | B1 |
6375848 | Cote et al. | Apr 2002 | B1 |
6423784 | Hamrock et al. | Jul 2002 | B1 |
6440303 | Spriegel | Aug 2002 | B2 |
D462699 | Johnson et al. | Sep 2002 | S |
6448062 | Huth et al. | Sep 2002 | B1 |
6465748 | Yamanashi et al. | Oct 2002 | B2 |
6491165 | Kuske et al. | Dec 2002 | B2 |
6495041 | Taniguchi et al. | Dec 2002 | B2 |
6524481 | Zha et al. | Feb 2003 | B2 |
6550747 | Rabie et al. | Apr 2003 | B2 |
6555005 | Zha et al. | Apr 2003 | B1 |
6595167 | Kaesgen | Jul 2003 | B2 |
6596167 | Ji et al. | Jul 2003 | B2 |
D478913 | Johnson et al. | Aug 2003 | S |
6602391 | Serikov | Aug 2003 | B2 |
6620319 | Behmann et al. | Sep 2003 | B2 |
6635104 | Komkova et al. | Oct 2003 | B2 |
6635179 | Summerton et al. | Oct 2003 | B1 |
6641733 | Zha et al. | Nov 2003 | B2 |
6645374 | Cote et al. | Nov 2003 | B2 |
6656356 | Gungerich et al. | Dec 2003 | B2 |
6682652 | Mahendran et al. | Jan 2004 | B2 |
6685832 | Mahendran et al. | Feb 2004 | B2 |
6699611 | Kim et al. | Mar 2004 | B2 |
6705465 | Ling et al. | Mar 2004 | B2 |
6721529 | Chen et al. | Apr 2004 | B2 |
6723758 | Stone et al. | Apr 2004 | B2 |
6727305 | Pavez Aranguiz | Apr 2004 | B1 |
6761013 | Tippey et al. | Jul 2004 | B2 |
6770202 | Kidd et al. | Aug 2004 | B1 |
6783008 | Zha et al. | Aug 2004 | B2 |
6790912 | Blong | Sep 2004 | B2 |
6793820 | McCray et al. | Sep 2004 | B1 |
6811696 | Wang et al. | Nov 2004 | B2 |
6821420 | Zha et al. | Nov 2004 | B2 |
6830782 | Kanazawa | Dec 2004 | B2 |
6851259 | Simburger et al. | Feb 2005 | B2 |
6861466 | Dadalas et al. | Mar 2005 | B2 |
6872305 | Johnson et al. | Mar 2005 | B2 |
6884350 | Muller | Apr 2005 | B2 |
6884375 | Wang et al. | Apr 2005 | B2 |
6890435 | Ji et al. | May 2005 | B2 |
6890645 | Disse et al. | May 2005 | B2 |
6893568 | Janson et al. | May 2005 | B1 |
6969465 | Zha et al. | Nov 2005 | B2 |
6974554 | Cox et al. | Dec 2005 | B2 |
6994867 | Hossainy et al. | Feb 2006 | B1 |
7000764 | Otsubo | Feb 2006 | B2 |
7041728 | Zipplies et al. | May 2006 | B2 |
7070909 | Japp et al. | Jul 2006 | B2 |
7226541 | Muller et al. | Jun 2007 | B2 |
7247238 | Mullette et al. | Jul 2007 | B2 |
7300022 | Muller | Nov 2007 | B2 |
7395646 | Salman et al. | Jul 2008 | B2 |
7404896 | Muller | Jul 2008 | B2 |
7449112 | Lee et al. | Nov 2008 | B2 |
7459085 | Koguma et al. | Dec 2008 | B2 |
7537718 | Mezhirov et al. | May 2009 | B2 |
7632439 | Mullette et al. | Dec 2009 | B2 |
7648034 | Charkoudian et al. | Jan 2010 | B2 |
7662212 | Mullette et al. | Feb 2010 | B2 |
7819956 | Muller | Oct 2010 | B2 |
7867417 | Mullette | Jan 2011 | B2 |
20020104439 | Komkova et al. | Aug 2002 | A1 |
20020148767 | Johnson et al. | Oct 2002 | A1 |
20030065302 | Kuroda et al. | Apr 2003 | A1 |
20030073970 | Suga | Apr 2003 | A1 |
20030178365 | Zha et al. | Sep 2003 | A1 |
20030226797 | Phelps | Dec 2003 | A1 |
20040084369 | Zha et al. | May 2004 | A1 |
20040092901 | Reece et al. | May 2004 | A1 |
20040145076 | Zha et al. | Jul 2004 | A1 |
20040167490 | Nelson et al. | Aug 2004 | A1 |
20040167493 | Jarpenberg et al. | Aug 2004 | A1 |
20040168947 | McDonald | Sep 2004 | A1 |
20040172002 | Nelson et al. | Sep 2004 | A1 |
20040176735 | Snell | Sep 2004 | A1 |
20040195172 | Yeh et al. | Oct 2004 | A1 |
20040217053 | Zha et al. | Nov 2004 | A1 |
20050015052 | Klippen et al. | Jan 2005 | A1 |
20050029185 | Muller | Feb 2005 | A1 |
20050032982 | Muller | Feb 2005 | A1 |
20050098494 | Mullette et al. | May 2005 | A1 |
20060157404 | Mullette et al. | Jul 2006 | A1 |
20060178480 | Tada et al. | Aug 2006 | A1 |
20060228483 | Abidine | Oct 2006 | A1 |
20070007197 | Mahendran et al. | Jan 2007 | A1 |
20080058440 | Muller et al. | Mar 2008 | A1 |
20080203018 | Muller et al. | Aug 2008 | A1 |
20080214687 | Muller et al. | Sep 2008 | A1 |
Number | Date | Country |
---|---|---|
897069 | Apr 1972 | CA |
2428457 | May 2002 | CA |
2440961 | Sep 2002 | CA |
1159770 | Sep 1997 | CN |
1552507 | Dec 2004 | CN |
3904544 | Aug 1990 | DE |
4007383 | Sep 1991 | DE |
4117281 | Jan 1992 | DE |
4113420 | Oct 1992 | DE |
4117422 | Nov 1992 | DE |
19503060 | Aug 1996 | DE |
29906389 | Jun 1999 | DE |
012557 | Feb 1983 | EP |
050447 | Oct 1985 | EP |
250337 | Dec 1987 | EP |
261734 | Mar 1988 | EP |
407900 | Jan 1991 | EP |
419396 | Mar 1991 | EP |
229019 | Sep 1991 | EP |
463627 | Jan 1992 | EP |
492942 | Jul 1992 | EP |
509663 | Oct 1992 | EP |
550798 | Jul 1993 | EP |
395133 | Feb 1995 | EP |
492446 | Nov 1995 | EP |
430082 | Jun 1996 | EP |
581168 | Oct 1996 | EP |
763758 | Mar 1997 | EP |
911073 | Apr 1999 | EP |
920904 | Jun 1999 | EP |
1034835 | Sep 2000 | EP |
1052012 | Nov 2000 | EP |
1236503 | Aug 2004 | EP |
2620712 | Mar 1989 | FR |
2674448 | Oct 1992 | FR |
2850297 | Jul 2004 | FR |
702911 | Jan 1954 | GB |
2253572 | Sep 1992 | GB |
2390042 | Dec 2003 | GB |
53-028083 | Mar 1978 | JP |
55129155 | Oct 1980 | JP |
58088007 | May 1983 | JP |
60260628 | Dec 1985 | JP |
61097006 | May 1986 | JP |
61107905 | May 1986 | JP |
61192309 | Aug 1986 | JP |
61257203 | Nov 1986 | JP |
61263605 | Nov 1986 | JP |
62004408 | Jan 1987 | JP |
62068828 | Mar 1987 | JP |
62114609 | May 1987 | JP |
62140607 | Jun 1987 | JP |
62179540 | Aug 1987 | JP |
62250908 | Oct 1987 | JP |
63097634 | Apr 1988 | JP |
S63-38884 | Oct 1988 | JP |
1075542 | Mar 1989 | JP |
01-307409 | Dec 1989 | JP |
2009498 | Jan 1990 | JP |
02031200 | Feb 1990 | JP |
02144132 | Jun 1990 | JP |
02164423 | Jun 1990 | JP |
02284035 | Nov 1990 | JP |
02302449 | Dec 1990 | JP |
03018373 | Jan 1991 | JP |
03110445 | May 1991 | JP |
03186325 | Aug 1991 | JP |
04022428 | Jan 1992 | JP |
H04-22428 | Jan 1992 | JP |
04187224 | Jul 1992 | JP |
04250898 | Sep 1992 | JP |
04265128 | Sep 1992 | JP |
04293528 | Oct 1992 | JP |
04300636 | Oct 1992 | JP |
04310223 | Nov 1992 | JP |
05023557 | Feb 1993 | JP |
05-96140 | Apr 1993 | JP |
05096136 | Apr 1993 | JP |
05115760 | May 1993 | JP |
05131124 | May 1993 | JP |
H05-115760 | May 1993 | JP |
05157654 | Jun 1993 | JP |
05285348 | Nov 1993 | JP |
06-027215 | Feb 1994 | JP |
06071120 | Mar 1994 | JP |
06114240 | Apr 1994 | JP |
06218237 | Aug 1994 | JP |
06285496 | Oct 1994 | JP |
06343837 | Dec 1994 | JP |
07000770 | Jan 1995 | JP |
07003043 | Jan 1995 | JP |
07024272 | Jan 1995 | JP |
07155570 | Jun 1995 | JP |
07155758 | Jun 1995 | JP |
07185268 | Jul 1995 | JP |
07185271 | Jul 1995 | JP |
07275665 | Oct 1995 | JP |
08010585 | Jan 1996 | JP |
08052331 | Feb 1996 | JP |
09141063 | Jun 1997 | JP |
09220569 | Aug 1997 | JP |
09324067 | Dec 1997 | JP |
09512857 | Dec 1997 | JP |
10156149 | Jun 1998 | JP |
11152366 | Jun 1999 | JP |
11165200 | Jun 1999 | JP |
11302438 | Nov 1999 | JP |
2000342932 | Dec 2000 | JP |
2004230280 | Aug 2004 | JP |
2004523338 | Aug 2004 | JP |
2005514517 | May 2005 | JP |
2005154551 | Jun 2005 | JP |
2005537120 | Dec 2005 | JP |
2006517469 | Jul 2006 | JP |
2002061017 | Jul 2002 | KR |
8806200 | Aug 1988 | WO |
9000434 | Jan 1990 | WO |
9117204 | Nov 1991 | WO |
9302779 | Feb 1993 | WO |
9315827 | Aug 1993 | WO |
9534424 | Dec 1995 | WO |
WO9603202 | Feb 1996 | WO |
9607470 | Mar 1996 | WO |
9614913 | May 1996 | WO |
9641676 | Dec 1996 | WO |
9822204 | May 1998 | WO |
9825694 | Jun 1998 | WO |
9828066 | Jul 1998 | WO |
9901207 | Jan 1999 | WO |
0043115 | Jul 2000 | WO |
0238256 | May 2002 | WO |
02087734 | Nov 2002 | WO |
03068374 | Aug 2003 | WO |
03080228 | Oct 2003 | WO |
03095078 | Nov 2003 | WO |
2004078327 | Sep 2004 | WO |
2004094049 | Nov 2004 | WO |
2005002712 | Jan 2005 | WO |
2005005028 | Jan 2005 | WO |
2005030916 | Apr 2005 | WO |
2006002479 | Jan 2006 | WO |
2006058384 | Jun 2006 | WO |
2006058394 | Jun 2006 | WO |
Number | Date | Country | |
---|---|---|---|
20100213117 A1 | Aug 2010 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 10564024 | US | |
Child | 12647734 | US |